diff --git a/clientapi/routing/routing.go b/clientapi/routing/routing.go
index 73206616..da2ccf2f 100644
--- a/clientapi/routing/routing.go
+++ b/clientapi/routing/routing.go
@@ -117,15 +117,22 @@ func Setup(
 		).Methods(http.MethodGet, http.MethodPost, http.MethodOptions)
 	}
 
-	r0mux := publicAPIMux.PathPrefix("/r0").Subrouter()
+	// You can't just do PathPrefix("/(r0|v3)") because regexps only apply when inside named path variables.
+	// So make a named path variable called 'apiversion' (which we will never read in handlers) and then do
+	// (r0|v3) - BUT this is a captured group, which makes no sense because you cannot extract this group
+	// from a match (gorilla/mux exposes no way to do this) so it demands you make it a non-capturing group
+	// using ?: so the final regexp becomes what is below. We also need a trailing slash to stop 'v33333' matching.
+	// Note that 'apiversion' is chosen because it must not collide with a variable used in any of the routing!
+	v3mux := publicAPIMux.PathPrefix("/{apiversion:(?:r0|v3)}/").Subrouter()
+
 	unstableMux := publicAPIMux.PathPrefix("/unstable").Subrouter()
 
-	r0mux.Handle("/createRoom",
+	v3mux.Handle("/createRoom",
 		httputil.MakeAuthAPI("createRoom", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			return CreateRoom(req, device, cfg, accountDB, rsAPI, asAPI)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
-	r0mux.Handle("/join/{roomIDOrAlias}",
+	v3mux.Handle("/join/{roomIDOrAlias}",
 		httputil.MakeAuthAPI(gomatrixserverlib.Join, userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			if r := rateLimits.Limit(req); r != nil {
 				return *r
@@ -141,7 +148,7 @@ func Setup(
 	).Methods(http.MethodPost, http.MethodOptions)
 
 	if mscCfg.Enabled("msc2753") {
-		r0mux.Handle("/peek/{roomIDOrAlias}",
+		v3mux.Handle("/peek/{roomIDOrAlias}",
 			httputil.MakeAuthAPI(gomatrixserverlib.Peek, userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 				if r := rateLimits.Limit(req); r != nil {
 					return *r
@@ -156,12 +163,12 @@ func Setup(
 			}),
 		).Methods(http.MethodPost, http.MethodOptions)
 	}
-	r0mux.Handle("/joined_rooms",
+	v3mux.Handle("/joined_rooms",
 		httputil.MakeAuthAPI("joined_rooms", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			return GetJoinedRooms(req, device, rsAPI)
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
-	r0mux.Handle("/rooms/{roomID}/join",
+	v3mux.Handle("/rooms/{roomID}/join",
 		httputil.MakeAuthAPI(gomatrixserverlib.Join, userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			if r := rateLimits.Limit(req); r != nil {
 				return *r
@@ -175,7 +182,7 @@ func Setup(
 			)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
-	r0mux.Handle("/rooms/{roomID}/leave",
+	v3mux.Handle("/rooms/{roomID}/leave",
 		httputil.MakeAuthAPI("membership", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			if r := rateLimits.Limit(req); r != nil {
 				return *r
@@ -189,7 +196,7 @@ func Setup(
 			)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
-	r0mux.Handle("/rooms/{roomID}/unpeek",
+	v3mux.Handle("/rooms/{roomID}/unpeek",
 		httputil.MakeAuthAPI("unpeek", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -200,7 +207,7 @@ func Setup(
 			)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
-	r0mux.Handle("/rooms/{roomID}/ban",
+	v3mux.Handle("/rooms/{roomID}/ban",
 		httputil.MakeAuthAPI("membership", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -209,7 +216,7 @@ func Setup(
 			return SendBan(req, accountDB, device, vars["roomID"], cfg, rsAPI, asAPI)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
-	r0mux.Handle("/rooms/{roomID}/invite",
+	v3mux.Handle("/rooms/{roomID}/invite",
 		httputil.MakeAuthAPI("membership", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			if r := rateLimits.Limit(req); r != nil {
 				return *r
@@ -221,7 +228,7 @@ func Setup(
 			return SendInvite(req, accountDB, device, vars["roomID"], cfg, rsAPI, asAPI)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
-	r0mux.Handle("/rooms/{roomID}/kick",
+	v3mux.Handle("/rooms/{roomID}/kick",
 		httputil.MakeAuthAPI("membership", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -230,7 +237,7 @@ func Setup(
 			return SendKick(req, accountDB, device, vars["roomID"], cfg, rsAPI, asAPI)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
-	r0mux.Handle("/rooms/{roomID}/unban",
+	v3mux.Handle("/rooms/{roomID}/unban",
 		httputil.MakeAuthAPI("membership", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -239,7 +246,7 @@ func Setup(
 			return SendUnban(req, accountDB, device, vars["roomID"], cfg, rsAPI, asAPI)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
-	r0mux.Handle("/rooms/{roomID}/send/{eventType}",
+	v3mux.Handle("/rooms/{roomID}/send/{eventType}",
 		httputil.MakeAuthAPI("send_message", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -248,7 +255,7 @@ func Setup(
 			return SendEvent(req, device, vars["roomID"], vars["eventType"], nil, nil, cfg, rsAPI, nil)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
-	r0mux.Handle("/rooms/{roomID}/send/{eventType}/{txnID}",
+	v3mux.Handle("/rooms/{roomID}/send/{eventType}/{txnID}",
 		httputil.MakeAuthAPI("send_message", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -259,7 +266,7 @@ func Setup(
 				nil, cfg, rsAPI, transactionsCache)
 		}),
 	).Methods(http.MethodPut, http.MethodOptions)
-	r0mux.Handle("/rooms/{roomID}/event/{eventID}",
+	v3mux.Handle("/rooms/{roomID}/event/{eventID}",
 		httputil.MakeAuthAPI("rooms_get_event", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -269,7 +276,7 @@ func Setup(
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/rooms/{roomID}/state", httputil.MakeAuthAPI("room_state", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
+	v3mux.Handle("/rooms/{roomID}/state", httputil.MakeAuthAPI("room_state", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 		vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 		if err != nil {
 			return util.ErrorResponse(err)
@@ -277,7 +284,7 @@ func Setup(
 		return OnIncomingStateRequest(req.Context(), device, rsAPI, vars["roomID"])
 	})).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/rooms/{roomID}/aliases", httputil.MakeAuthAPI("aliases", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
+	v3mux.Handle("/rooms/{roomID}/aliases", httputil.MakeAuthAPI("aliases", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 		vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 		if err != nil {
 			return util.ErrorResponse(err)
@@ -285,7 +292,7 @@ func Setup(
 		return GetAliases(req, rsAPI, device, vars["roomID"])
 	})).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/rooms/{roomID}/state/{type:[^/]+/?}", httputil.MakeAuthAPI("room_state", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
+	v3mux.Handle("/rooms/{roomID}/state/{type:[^/]+/?}", httputil.MakeAuthAPI("room_state", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 		vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 		if err != nil {
 			return util.ErrorResponse(err)
@@ -296,7 +303,7 @@ func Setup(
 		return OnIncomingStateTypeRequest(req.Context(), device, rsAPI, vars["roomID"], eventType, "", eventFormat)
 	})).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/rooms/{roomID}/state/{type}/{stateKey}", httputil.MakeAuthAPI("room_state", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
+	v3mux.Handle("/rooms/{roomID}/state/{type}/{stateKey}", httputil.MakeAuthAPI("room_state", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 		vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 		if err != nil {
 			return util.ErrorResponse(err)
@@ -305,7 +312,7 @@ func Setup(
 		return OnIncomingStateTypeRequest(req.Context(), device, rsAPI, vars["roomID"], vars["type"], vars["stateKey"], eventFormat)
 	})).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/rooms/{roomID}/state/{eventType:[^/]+/?}",
+	v3mux.Handle("/rooms/{roomID}/state/{eventType:[^/]+/?}",
 		httputil.MakeAuthAPI("send_message", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -317,7 +324,7 @@ func Setup(
 		}),
 	).Methods(http.MethodPut, http.MethodOptions)
 
-	r0mux.Handle("/rooms/{roomID}/state/{eventType}/{stateKey}",
+	v3mux.Handle("/rooms/{roomID}/state/{eventType}/{stateKey}",
 		httputil.MakeAuthAPI("send_message", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -328,21 +335,21 @@ func Setup(
 		}),
 	).Methods(http.MethodPut, http.MethodOptions)
 
-	r0mux.Handle("/register", httputil.MakeExternalAPI("register", func(req *http.Request) util.JSONResponse {
+	v3mux.Handle("/register", httputil.MakeExternalAPI("register", func(req *http.Request) util.JSONResponse {
 		if r := rateLimits.Limit(req); r != nil {
 			return *r
 		}
 		return Register(req, userAPI, accountDB, cfg)
 	})).Methods(http.MethodPost, http.MethodOptions)
 
-	r0mux.Handle("/register/available", httputil.MakeExternalAPI("registerAvailable", func(req *http.Request) util.JSONResponse {
+	v3mux.Handle("/register/available", httputil.MakeExternalAPI("registerAvailable", func(req *http.Request) util.JSONResponse {
 		if r := rateLimits.Limit(req); r != nil {
 			return *r
 		}
 		return RegisterAvailable(req, cfg, accountDB)
 	})).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/directory/room/{roomAlias}",
+	v3mux.Handle("/directory/room/{roomAlias}",
 		httputil.MakeExternalAPI("directory_room", func(req *http.Request) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -352,7 +359,7 @@ func Setup(
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/directory/room/{roomAlias}",
+	v3mux.Handle("/directory/room/{roomAlias}",
 		httputil.MakeAuthAPI("directory_room", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -362,7 +369,7 @@ func Setup(
 		}),
 	).Methods(http.MethodPut, http.MethodOptions)
 
-	r0mux.Handle("/directory/room/{roomAlias}",
+	v3mux.Handle("/directory/room/{roomAlias}",
 		httputil.MakeAuthAPI("directory_room", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -371,7 +378,7 @@ func Setup(
 			return RemoveLocalAlias(req, device, vars["roomAlias"], rsAPI)
 		}),
 	).Methods(http.MethodDelete, http.MethodOptions)
-	r0mux.Handle("/directory/list/room/{roomID}",
+	v3mux.Handle("/directory/list/room/{roomID}",
 		httputil.MakeExternalAPI("directory_list", func(req *http.Request) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -381,7 +388,7 @@ func Setup(
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 	// TODO: Add AS support
-	r0mux.Handle("/directory/list/room/{roomID}",
+	v3mux.Handle("/directory/list/room/{roomID}",
 		httputil.MakeAuthAPI("directory_list", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -390,25 +397,25 @@ func Setup(
 			return SetVisibility(req, rsAPI, device, vars["roomID"])
 		}),
 	).Methods(http.MethodPut, http.MethodOptions)
-	r0mux.Handle("/publicRooms",
+	v3mux.Handle("/publicRooms",
 		httputil.MakeExternalAPI("public_rooms", func(req *http.Request) util.JSONResponse {
 			return GetPostPublicRooms(req, rsAPI, extRoomsProvider, federation, cfg)
 		}),
 	).Methods(http.MethodGet, http.MethodPost, http.MethodOptions)
 
-	r0mux.Handle("/logout",
+	v3mux.Handle("/logout",
 		httputil.MakeAuthAPI("logout", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			return Logout(req, userAPI, device)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
 
-	r0mux.Handle("/logout/all",
+	v3mux.Handle("/logout/all",
 		httputil.MakeAuthAPI("logout", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			return LogoutAll(req, userAPI, device)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
 
-	r0mux.Handle("/rooms/{roomID}/typing/{userID}",
+	v3mux.Handle("/rooms/{roomID}/typing/{userID}",
 		httputil.MakeAuthAPI("rooms_typing", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			if r := rateLimits.Limit(req); r != nil {
 				return *r
@@ -420,7 +427,7 @@ func Setup(
 			return SendTyping(req, device, vars["roomID"], vars["userID"], accountDB, eduAPI, rsAPI)
 		}),
 	).Methods(http.MethodPut, http.MethodOptions)
-	r0mux.Handle("/rooms/{roomID}/redact/{eventID}",
+	v3mux.Handle("/rooms/{roomID}/redact/{eventID}",
 		httputil.MakeAuthAPI("rooms_redact", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -429,7 +436,7 @@ func Setup(
 			return SendRedaction(req, device, vars["roomID"], vars["eventID"], cfg, rsAPI)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
-	r0mux.Handle("/rooms/{roomID}/redact/{eventID}/{txnId}",
+	v3mux.Handle("/rooms/{roomID}/redact/{eventID}/{txnId}",
 		httputil.MakeAuthAPI("rooms_redact", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -439,7 +446,7 @@ func Setup(
 		}),
 	).Methods(http.MethodPut, http.MethodOptions)
 
-	r0mux.Handle("/sendToDevice/{eventType}/{txnID}",
+	v3mux.Handle("/sendToDevice/{eventType}/{txnID}",
 		httputil.MakeAuthAPI("send_to_device", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -464,7 +471,7 @@ func Setup(
 		}),
 	).Methods(http.MethodPut, http.MethodOptions)
 
-	r0mux.Handle("/account/whoami",
+	v3mux.Handle("/account/whoami",
 		httputil.MakeAuthAPI("whoami", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			if r := rateLimits.Limit(req); r != nil {
 				return *r
@@ -473,7 +480,7 @@ func Setup(
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/account/password",
+	v3mux.Handle("/account/password",
 		httputil.MakeAuthAPI("password", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			if r := rateLimits.Limit(req); r != nil {
 				return *r
@@ -482,7 +489,7 @@ func Setup(
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
 
-	r0mux.Handle("/account/deactivate",
+	v3mux.Handle("/account/deactivate",
 		httputil.MakeAuthAPI("deactivate", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			if r := rateLimits.Limit(req); r != nil {
 				return *r
@@ -493,7 +500,7 @@ func Setup(
 
 	// Stub endpoints required by Element
 
-	r0mux.Handle("/login",
+	v3mux.Handle("/login",
 		httputil.MakeExternalAPI("login", func(req *http.Request) util.JSONResponse {
 			if r := rateLimits.Limit(req); r != nil {
 				return *r
@@ -502,14 +509,14 @@ func Setup(
 		}),
 	).Methods(http.MethodGet, http.MethodPost, http.MethodOptions)
 
-	r0mux.Handle("/auth/{authType}/fallback/web",
+	v3mux.Handle("/auth/{authType}/fallback/web",
 		httputil.MakeHTMLAPI("auth_fallback", func(w http.ResponseWriter, req *http.Request) *util.JSONResponse {
 			vars := mux.Vars(req)
 			return AuthFallback(w, req, vars["authType"], cfg)
 		}),
 	).Methods(http.MethodGet, http.MethodPost, http.MethodOptions)
 
-	r0mux.Handle("/pushrules/",
+	v3mux.Handle("/pushrules/",
 		httputil.MakeExternalAPI("push_rules", func(req *http.Request) util.JSONResponse {
 			// TODO: Implement push rules API
 			res := json.RawMessage(`{
@@ -530,7 +537,7 @@ func Setup(
 
 	// Element user settings
 
-	r0mux.Handle("/profile/{userID}",
+	v3mux.Handle("/profile/{userID}",
 		httputil.MakeExternalAPI("profile", func(req *http.Request) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -540,7 +547,7 @@ func Setup(
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/profile/{userID}/avatar_url",
+	v3mux.Handle("/profile/{userID}/avatar_url",
 		httputil.MakeExternalAPI("profile_avatar_url", func(req *http.Request) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -550,7 +557,7 @@ func Setup(
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/profile/{userID}/avatar_url",
+	v3mux.Handle("/profile/{userID}/avatar_url",
 		httputil.MakeAuthAPI("profile_avatar_url", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			if r := rateLimits.Limit(req); r != nil {
 				return *r
@@ -565,7 +572,7 @@ func Setup(
 	// Browsers use the OPTIONS HTTP method to check if the CORS policy allows
 	// PUT requests, so we need to allow this method
 
-	r0mux.Handle("/profile/{userID}/displayname",
+	v3mux.Handle("/profile/{userID}/displayname",
 		httputil.MakeExternalAPI("profile_displayname", func(req *http.Request) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -575,7 +582,7 @@ func Setup(
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/profile/{userID}/displayname",
+	v3mux.Handle("/profile/{userID}/displayname",
 		httputil.MakeAuthAPI("profile_displayname", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			if r := rateLimits.Limit(req); r != nil {
 				return *r
@@ -590,13 +597,13 @@ func Setup(
 	// Browsers use the OPTIONS HTTP method to check if the CORS policy allows
 	// PUT requests, so we need to allow this method
 
-	r0mux.Handle("/account/3pid",
+	v3mux.Handle("/account/3pid",
 		httputil.MakeAuthAPI("account_3pid", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			return GetAssociated3PIDs(req, accountDB, device)
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/account/3pid",
+	v3mux.Handle("/account/3pid",
 		httputil.MakeAuthAPI("account_3pid", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			return CheckAndSave3PIDAssociation(req, accountDB, device, cfg)
 		}),
@@ -608,14 +615,14 @@ func Setup(
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
 
-	r0mux.Handle("/{path:(?:account/3pid|register)}/email/requestToken",
+	v3mux.Handle("/{path:(?:account/3pid|register)}/email/requestToken",
 		httputil.MakeExternalAPI("account_3pid_request_token", func(req *http.Request) util.JSONResponse {
 			return RequestEmailToken(req, accountDB, cfg)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
 
 	// Element logs get flooded unless this is handled
-	r0mux.Handle("/presence/{userID}/status",
+	v3mux.Handle("/presence/{userID}/status",
 		httputil.MakeExternalAPI("presence", func(req *http.Request) util.JSONResponse {
 			if r := rateLimits.Limit(req); r != nil {
 				return *r
@@ -628,7 +635,7 @@ func Setup(
 		}),
 	).Methods(http.MethodPut, http.MethodOptions)
 
-	r0mux.Handle("/voip/turnServer",
+	v3mux.Handle("/voip/turnServer",
 		httputil.MakeAuthAPI("turn_server", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			if r := rateLimits.Limit(req); r != nil {
 				return *r
@@ -637,7 +644,7 @@ func Setup(
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/thirdparty/protocols",
+	v3mux.Handle("/thirdparty/protocols",
 		httputil.MakeExternalAPI("thirdparty_protocols", func(req *http.Request) util.JSONResponse {
 			// TODO: Return the third party protcols
 			return util.JSONResponse{
@@ -647,7 +654,7 @@ func Setup(
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/rooms/{roomID}/initialSync",
+	v3mux.Handle("/rooms/{roomID}/initialSync",
 		httputil.MakeExternalAPI("rooms_initial_sync", func(req *http.Request) util.JSONResponse {
 			// TODO: Allow people to peek into rooms.
 			return util.JSONResponse{
@@ -657,7 +664,7 @@ func Setup(
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/user/{userID}/account_data/{type}",
+	v3mux.Handle("/user/{userID}/account_data/{type}",
 		httputil.MakeAuthAPI("user_account_data", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -667,7 +674,7 @@ func Setup(
 		}),
 	).Methods(http.MethodPut, http.MethodOptions)
 
-	r0mux.Handle("/user/{userID}/rooms/{roomID}/account_data/{type}",
+	v3mux.Handle("/user/{userID}/rooms/{roomID}/account_data/{type}",
 		httputil.MakeAuthAPI("user_account_data", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -677,7 +684,7 @@ func Setup(
 		}),
 	).Methods(http.MethodPut, http.MethodOptions)
 
-	r0mux.Handle("/user/{userID}/account_data/{type}",
+	v3mux.Handle("/user/{userID}/account_data/{type}",
 		httputil.MakeAuthAPI("user_account_data", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -687,7 +694,7 @@ func Setup(
 		}),
 	).Methods(http.MethodGet)
 
-	r0mux.Handle("/user/{userID}/rooms/{roomID}/account_data/{type}",
+	v3mux.Handle("/user/{userID}/rooms/{roomID}/account_data/{type}",
 		httputil.MakeAuthAPI("user_account_data", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -697,7 +704,7 @@ func Setup(
 		}),
 	).Methods(http.MethodGet)
 
-	r0mux.Handle("/admin/whois/{userID}",
+	v3mux.Handle("/admin/whois/{userID}",
 		httputil.MakeAuthAPI("admin_whois", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -707,7 +714,7 @@ func Setup(
 		}),
 	).Methods(http.MethodGet)
 
-	r0mux.Handle("/user/{userID}/openid/request_token",
+	v3mux.Handle("/user/{userID}/openid/request_token",
 		httputil.MakeAuthAPI("openid_request_token", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			if r := rateLimits.Limit(req); r != nil {
 				return *r
@@ -720,7 +727,7 @@ func Setup(
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
 
-	r0mux.Handle("/user_directory/search",
+	v3mux.Handle("/user_directory/search",
 		httputil.MakeAuthAPI("userdirectory_search", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			if r := rateLimits.Limit(req); r != nil {
 				return *r
@@ -745,7 +752,7 @@ func Setup(
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
 
-	r0mux.Handle("/rooms/{roomID}/members",
+	v3mux.Handle("/rooms/{roomID}/members",
 		httputil.MakeAuthAPI("rooms_members", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -755,7 +762,7 @@ func Setup(
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/rooms/{roomID}/joined_members",
+	v3mux.Handle("/rooms/{roomID}/joined_members",
 		httputil.MakeAuthAPI("rooms_members", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -765,7 +772,7 @@ func Setup(
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/rooms/{roomID}/read_markers",
+	v3mux.Handle("/rooms/{roomID}/read_markers",
 		httputil.MakeAuthAPI("rooms_read_markers", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			if r := rateLimits.Limit(req); r != nil {
 				return *r
@@ -778,7 +785,7 @@ func Setup(
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
 
-	r0mux.Handle("/rooms/{roomID}/forget",
+	v3mux.Handle("/rooms/{roomID}/forget",
 		httputil.MakeAuthAPI("rooms_forget", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			if r := rateLimits.Limit(req); r != nil {
 				return *r
@@ -791,13 +798,13 @@ func Setup(
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
 
-	r0mux.Handle("/devices",
+	v3mux.Handle("/devices",
 		httputil.MakeAuthAPI("get_devices", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			return GetDevicesByLocalpart(req, userAPI, device)
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/devices/{deviceID}",
+	v3mux.Handle("/devices/{deviceID}",
 		httputil.MakeAuthAPI("get_device", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -807,7 +814,7 @@ func Setup(
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/devices/{deviceID}",
+	v3mux.Handle("/devices/{deviceID}",
 		httputil.MakeAuthAPI("device_data", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -817,7 +824,7 @@ func Setup(
 		}),
 	).Methods(http.MethodPut, http.MethodOptions)
 
-	r0mux.Handle("/devices/{deviceID}",
+	v3mux.Handle("/devices/{deviceID}",
 		httputil.MakeAuthAPI("delete_device", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -827,14 +834,14 @@ func Setup(
 		}),
 	).Methods(http.MethodDelete, http.MethodOptions)
 
-	r0mux.Handle("/delete_devices",
+	v3mux.Handle("/delete_devices",
 		httputil.MakeAuthAPI("delete_devices", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			return DeleteDevices(req, userAPI, device)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
 
 	// Stub implementations for sytest
-	r0mux.Handle("/events",
+	v3mux.Handle("/events",
 		httputil.MakeExternalAPI("events", func(req *http.Request) util.JSONResponse {
 			return util.JSONResponse{Code: http.StatusOK, JSON: map[string]interface{}{
 				"chunk": []interface{}{},
@@ -844,7 +851,7 @@ func Setup(
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/initialSync",
+	v3mux.Handle("/initialSync",
 		httputil.MakeExternalAPI("initial_sync", func(req *http.Request) util.JSONResponse {
 			return util.JSONResponse{Code: http.StatusOK, JSON: map[string]interface{}{
 				"end": "",
@@ -852,7 +859,7 @@ func Setup(
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/user/{userId}/rooms/{roomId}/tags",
+	v3mux.Handle("/user/{userId}/rooms/{roomId}/tags",
 		httputil.MakeAuthAPI("get_tags", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -862,7 +869,7 @@ func Setup(
 		}),
 	).Methods(http.MethodGet, http.MethodOptions)
 
-	r0mux.Handle("/user/{userId}/rooms/{roomId}/tags/{tag}",
+	v3mux.Handle("/user/{userId}/rooms/{roomId}/tags/{tag}",
 		httputil.MakeAuthAPI("put_tag", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -872,7 +879,7 @@ func Setup(
 		}),
 	).Methods(http.MethodPut, http.MethodOptions)
 
-	r0mux.Handle("/user/{userId}/rooms/{roomId}/tags/{tag}",
+	v3mux.Handle("/user/{userId}/rooms/{roomId}/tags/{tag}",
 		httputil.MakeAuthAPI("delete_tag", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
 			if err != nil {
@@ -882,7 +889,7 @@ func Setup(
 		}),
 	).Methods(http.MethodDelete, http.MethodOptions)
 
-	r0mux.Handle("/capabilities",
+	v3mux.Handle("/capabilities",
 		httputil.MakeAuthAPI("capabilities", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			if r := rateLimits.Limit(req); r != nil {
 				return *r
@@ -925,11 +932,11 @@ func Setup(
 		return CreateKeyBackupVersion(req, userAPI, device)
 	})
 
-	r0mux.Handle("/room_keys/version/{version}", getBackupKeysVersion).Methods(http.MethodGet, http.MethodOptions)
-	r0mux.Handle("/room_keys/version", getLatestBackupKeysVersion).Methods(http.MethodGet, http.MethodOptions)
-	r0mux.Handle("/room_keys/version/{version}", putBackupKeysVersion).Methods(http.MethodPut)
-	r0mux.Handle("/room_keys/version/{version}", deleteBackupKeysVersion).Methods(http.MethodDelete)
-	r0mux.Handle("/room_keys/version", postNewBackupKeysVersion).Methods(http.MethodPost, http.MethodOptions)
+	v3mux.Handle("/room_keys/version/{version}", getBackupKeysVersion).Methods(http.MethodGet, http.MethodOptions)
+	v3mux.Handle("/room_keys/version", getLatestBackupKeysVersion).Methods(http.MethodGet, http.MethodOptions)
+	v3mux.Handle("/room_keys/version/{version}", putBackupKeysVersion).Methods(http.MethodPut)
+	v3mux.Handle("/room_keys/version/{version}", deleteBackupKeysVersion).Methods(http.MethodDelete)
+	v3mux.Handle("/room_keys/version", postNewBackupKeysVersion).Methods(http.MethodPost, http.MethodOptions)
 
 	unstableMux.Handle("/room_keys/version/{version}", getBackupKeysVersion).Methods(http.MethodGet, http.MethodOptions)
 	unstableMux.Handle("/room_keys/version", getLatestBackupKeysVersion).Methods(http.MethodGet, http.MethodOptions)
@@ -1021,9 +1028,9 @@ func Setup(
 		return UploadBackupKeys(req, userAPI, device, version, &keyReq)
 	})
 
-	r0mux.Handle("/room_keys/keys", putBackupKeys).Methods(http.MethodPut)
-	r0mux.Handle("/room_keys/keys/{roomID}", putBackupKeysRoom).Methods(http.MethodPut)
-	r0mux.Handle("/room_keys/keys/{roomID}/{sessionID}", putBackupKeysRoomSession).Methods(http.MethodPut)
+	v3mux.Handle("/room_keys/keys", putBackupKeys).Methods(http.MethodPut)
+	v3mux.Handle("/room_keys/keys/{roomID}", putBackupKeysRoom).Methods(http.MethodPut)
+	v3mux.Handle("/room_keys/keys/{roomID}/{sessionID}", putBackupKeysRoomSession).Methods(http.MethodPut)
 
 	unstableMux.Handle("/room_keys/keys", putBackupKeys).Methods(http.MethodPut)
 	unstableMux.Handle("/room_keys/keys/{roomID}", putBackupKeysRoom).Methods(http.MethodPut)
@@ -1051,9 +1058,9 @@ func Setup(
 		return GetBackupKeys(req, userAPI, device, req.URL.Query().Get("version"), vars["roomID"], vars["sessionID"])
 	})
 
-	r0mux.Handle("/room_keys/keys", getBackupKeys).Methods(http.MethodGet, http.MethodOptions)
-	r0mux.Handle("/room_keys/keys/{roomID}", getBackupKeysRoom).Methods(http.MethodGet, http.MethodOptions)
-	r0mux.Handle("/room_keys/keys/{roomID}/{sessionID}", getBackupKeysRoomSession).Methods(http.MethodGet, http.MethodOptions)
+	v3mux.Handle("/room_keys/keys", getBackupKeys).Methods(http.MethodGet, http.MethodOptions)
+	v3mux.Handle("/room_keys/keys/{roomID}", getBackupKeysRoom).Methods(http.MethodGet, http.MethodOptions)
+	v3mux.Handle("/room_keys/keys/{roomID}/{sessionID}", getBackupKeysRoomSession).Methods(http.MethodGet, http.MethodOptions)
 
 	unstableMux.Handle("/room_keys/keys", getBackupKeys).Methods(http.MethodGet, http.MethodOptions)
 	unstableMux.Handle("/room_keys/keys/{roomID}", getBackupKeysRoom).Methods(http.MethodGet, http.MethodOptions)
@@ -1071,34 +1078,34 @@ func Setup(
 		return UploadCrossSigningDeviceSignatures(req, keyAPI, device)
 	})
 
-	r0mux.Handle("/keys/device_signing/upload", postDeviceSigningKeys).Methods(http.MethodPost, http.MethodOptions)
-	r0mux.Handle("/keys/signatures/upload", postDeviceSigningSignatures).Methods(http.MethodPost, http.MethodOptions)
+	v3mux.Handle("/keys/device_signing/upload", postDeviceSigningKeys).Methods(http.MethodPost, http.MethodOptions)
+	v3mux.Handle("/keys/signatures/upload", postDeviceSigningSignatures).Methods(http.MethodPost, http.MethodOptions)
 
 	unstableMux.Handle("/keys/device_signing/upload", postDeviceSigningKeys).Methods(http.MethodPost, http.MethodOptions)
 	unstableMux.Handle("/keys/signatures/upload", postDeviceSigningSignatures).Methods(http.MethodPost, http.MethodOptions)
 
 	// Supplying a device ID is deprecated.
-	r0mux.Handle("/keys/upload/{deviceID}",
+	v3mux.Handle("/keys/upload/{deviceID}",
 		httputil.MakeAuthAPI("keys_upload", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			return UploadKeys(req, keyAPI, device)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
-	r0mux.Handle("/keys/upload",
+	v3mux.Handle("/keys/upload",
 		httputil.MakeAuthAPI("keys_upload", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			return UploadKeys(req, keyAPI, device)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
-	r0mux.Handle("/keys/query",
+	v3mux.Handle("/keys/query",
 		httputil.MakeAuthAPI("keys_query", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			return QueryKeys(req, keyAPI, device)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
-	r0mux.Handle("/keys/claim",
+	v3mux.Handle("/keys/claim",
 		httputil.MakeAuthAPI("keys_claim", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			return ClaimKeys(req, keyAPI)
 		}),
 	).Methods(http.MethodPost, http.MethodOptions)
-	r0mux.Handle("/rooms/{roomId}/receipt/{receiptType}/{eventId}",
+	v3mux.Handle("/rooms/{roomId}/receipt/{receiptType}/{eventId}",
 		httputil.MakeAuthAPI(gomatrixserverlib.Join, userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			if r := rateLimits.Limit(req); r != nil {
 				return *r