diff --git a/app/src/frontend/app.tsx b/app/src/frontend/app.tsx
index c2df0a9f..ad5257ae 100644
--- a/app/src/frontend/app.tsx
+++ b/app/src/frontend/app.tsx
@@ -1,31 +1,30 @@
 import React, { Fragment } from 'react';
 import { Route, Switch, Link } from 'react-router-dom';
 import PropTypes from 'prop-types';
-import { parse } from 'query-string';
 
 import '../../node_modules/bootstrap/dist/css/bootstrap.min.css';
 import './app.css';
 
-import BuildingView from './building/building-view';
-import ColouringMap from './map/map';
 import Header from './header';
-import MultiEdit from './building/multi-edit';
-import Categories from './building/categories';
-import Sidebar from './building/sidebar';
 
 import AboutPage from './pages/about';
 import ContributorAgreementPage from './pages/contributor-agreement';
 import PrivacyPolicyPage from './pages/privacy-policy';
-import Welcome from './pages/welcome';
 
 import Login from './user/login';
 import MyAccountPage from './user/my-account';
 import SignUp from './user/signup';
-
 import ForgottenPassword from './user/forgotten-password';
 import PasswordReset from './user/password-reset';
 
-import { parseCategoryURL } from '../parse';
+import MapApp from './map-app';
+
+
+interface AppProps {
+    user?: any;
+    building?: any;
+    building_like?: boolean;
+}
 
 /**
  * App component
@@ -39,35 +38,28 @@ import { parseCategoryURL } from '../parse';
  *   map or other pages are rendered, based on the URL. Use a react-router-dom <Link /> in
  *   child components to navigate without a full page reload.
  */
-class App extends React.Component<any, any> { // TODO: add proper types
+class App extends React.Component<AppProps, any> { // TODO: add proper types
     static propTypes = { // TODO: generate propTypes from TS
         user: PropTypes.object,
         building: PropTypes.object,
         building_like: PropTypes.bool
-    }
+    };
 
-    constructor(props) {
+    constructor(props: Readonly<AppProps>) {
         super(props);
-        // set building revision id, default 0
-        const rev = (props.building)? +props.building.revision_id : 0;
+        
         this.state = {
-            user: props.user,
-            building: props.building,
-            building_like: props.building_like,
-            revision_id: rev
+            user: props.user
         };
         this.login = this.login.bind(this);
         this.updateUser = this.updateUser.bind(this);
         this.logout = this.logout.bind(this);
-        this.selectBuilding = this.selectBuilding.bind(this);
-        this.colourBuilding = this.colourBuilding.bind(this);
-        this.increaseRevision = this.increaseRevision.bind(this);
     }
 
     login(user) {
         if (user.error) {
             this.logout();
-            return
+            return;
         }
         this.setState({user: user});
     }
@@ -80,171 +72,12 @@ class App extends React.Component<any, any> { // TODO: add proper types
         this.setState({user: undefined});
     }
 
-    increaseRevision(revisionId) {
-        revisionId = +revisionId;
-        // bump revision id, only ever increasing
-        if (revisionId > this.state.revision_id){
-            this.setState({revision_id: revisionId})
-        }
-    }
-
-    selectBuilding(building) {
-        this.increaseRevision(building.revision_id);
-        // get UPRNs and update
-        fetch(`/api/buildings/${building.building_id}/uprns.json`, {
-            method: 'GET',
-            headers:{
-                'Content-Type': 'application/json'
-            },
-            credentials: 'same-origin'
-        }).then(
-            res => res.json()
-        ).then((res) => {
-            if (res.error) {
-                console.error(res);
-            } else {
-                building.uprns = res.uprns;
-                this.setState({building: building});
-            }
-        }).catch((err) => {
-            console.error(err)
-            this.setState({building: building});
-        });
-
-        // get if liked and update
-        fetch(`/api/buildings/${building.building_id}/like.json`, {
-            method: 'GET',
-            headers:{
-                'Content-Type': 'application/json'
-            },
-            credentials: 'same-origin'
-        }).then(
-            res => res.json()
-        ).then((res) => {
-            if (res.error) {
-                console.error(res);
-            } else {
-                this.setState({building_like: res.like});
-            }
-        }).catch((err) => {
-            console.error(err)
-            this.setState({building_like: false});
-        });
-    }
-
-    /**
-     * Colour building
-     *
-     * Used in multi-edit mode to colour buildings on map click
-     *
-     * Pulls data from URL to form update
-     *
-     * @param {object} building
-     */
-    colourBuilding(building) {
-        const cat = parseCategoryURL(window.location.pathname);
-        const q = parse(window.location.search);
-        const data = (cat === 'like')? {like: true}: JSON.parse(q.data as string); // TODO: verify what happens if data is string[]
-        if (cat === 'like'){
-            this.likeBuilding(building.building_id)
-        } else {
-            this.updateBuilding(building.building_id, data)
-        }
-    }
-
-    likeBuilding(buildingId) {
-        fetch(`/api/buildings/${buildingId}/like.json`, {
-            method: 'POST',
-            headers:{
-                'Content-Type': 'application/json'
-            },
-            credentials: 'same-origin',
-            body: JSON.stringify({like: true})
-        }).then(
-            res => res.json()
-        ).then(function(res){
-            if (res.error) {
-                console.error({error: res.error})
-            } else {
-                this.increaseRevision(res.revision_id);
-            }
-        }.bind(this)).catch(
-            (err) => console.error({error: err})
-        );
-    }
-
-    updateBuilding(buildingId, data){
-        fetch(`/api/buildings/${buildingId}.json`, {
-            method: 'POST',
-            body: JSON.stringify(data),
-            headers:{
-                'Content-Type': 'application/json'
-            },
-            credentials: 'same-origin'
-        }).then(
-            res => res.json()
-        ).then(res => {
-            if (res.error) {
-                console.error({error: res.error})
-            } else {
-                this.increaseRevision(res.revision_id);
-            }
-        }).catch(
-            (err) => console.error({error: err})
-        );
-    }
-
     render() {
-        const building_id = (this.state.building)?
-            this.state.building.building_id
-            : 2503371 // Default to UCL main building. TODO use last selected if any
-        const building = this.state.building;
-        const building_like = this.state.building_like;
         return (
             <Fragment>
             <Header user={this.state.user} />
             <main>
             <Switch>
-                <Route exact path="/">
-                    <Welcome />
-                </Route>
-                <Route exact path="/view/categories.html">
-                    <Sidebar>
-                        <Categories mode="view" building_id={building_id} />
-                    </Sidebar>
-                </Route>
-                <Route exact path="/edit/categories.html">
-                    <Sidebar>
-                        <Categories mode="edit" building_id={building_id} />
-                    </Sidebar>
-                </Route>
-                <Route exact path="/multi-edit/:cat.html" render={(props) => (
-                    <MultiEdit
-                        {...props}
-                        user={this.state.user}
-                    />
-                ) } />
-                <Route exact path="/:mode/:cat/building/:building.html" render={(props) => (
-                    <BuildingView
-                        mode={props.match.params.mode}
-                        cat={props.match.params.cat}
-                        building={this.state.building}
-                        building_like={this.state.building_like}
-                        selectBuilding={this.selectBuilding}
-                        user={this.state.user}
-                    />
-                ) } />
-            </Switch>
-            <Switch>
-                <Route exact path="/(multi-edit.*|edit.*|view.*)?" render={(props) => (
-                    <ColouringMap
-                        {...props}
-                        building={this.state.building}
-                        revision_id={this.state.revision_id}
-                        selectBuilding={this.selectBuilding}
-                        colourBuilding={this.colourBuilding}
-                    />
-                ) } />
                 <Route exact path="/about.html" component={AboutPage} />
                 <Route exact path="/login.html">
                     <Login user={this.state.user} login={this.login} />
@@ -263,6 +96,14 @@ class App extends React.Component<any, any> { // TODO: add proper types
                 </Route>
                 <Route exact path="/privacy-policy.html" component={PrivacyPolicyPage} />
                 <Route exact path="/contributor-agreement.html" component={ContributorAgreementPage} />
+                <Route exact path="/:mode?/:category?/:building?" render={(props) => (
+                    <MapApp
+                        {...props}
+                        building={this.props.building}
+                        building_like={this.props.building_like}
+                        user={this.state.user}
+                    />
+                )} />
                 <Route component={NotFound} />
             </Switch>
             </main>
diff --git a/app/src/frontend/map-app.tsx b/app/src/frontend/map-app.tsx
new file mode 100644
index 00000000..89306535
--- /dev/null
+++ b/app/src/frontend/map-app.tsx
@@ -0,0 +1,250 @@
+import React, { Fragment } from 'react';
+import { Switch, Route, RouteComponentProps, Redirect } from 'react-router-dom';
+import PropTypes from 'prop-types';
+
+import Welcome from './pages/welcome';
+import Sidebar from './building/sidebar';
+import Categories from './building/categories';
+import MultiEdit from './building/multi-edit';
+import BuildingView from './building/building-view';
+import ColouringMap from './map/map';
+import { parse } from 'query-string';
+
+interface MapAppRouteParams {
+    mode: 'view' | 'edit' | 'multi-edit';
+    category: string;
+    building?: string;
+}
+
+interface MapAppProps extends RouteComponentProps<MapAppRouteParams> {
+    building: any;
+    building_like: boolean;
+    user: any;
+}
+
+interface MapAppState {
+    category: string;
+    revision_id: number;
+    building: any;
+    building_like: boolean;
+}
+
+class MapApp extends React.Component<MapAppProps, MapAppState> {
+    static propTypes = {
+        category: PropTypes.string,
+        revision_id: PropTypes.number,
+        building: PropTypes.object,
+        building_like: PropTypes.bool,
+        user: PropTypes.object
+    };
+    constructor(props: Readonly<MapAppProps>) {
+        super(props);
+
+        // set building revision id, default 0
+        const rev = props.building != undefined ? +props.building.revision_id : 0;
+
+        this.state = {
+            category: this.getCategory(props.match.params.category),
+            revision_id: rev,
+            building: props.building,
+            building_like: props.building_like
+        };
+
+        this.selectBuilding = this.selectBuilding.bind(this);
+        this.colourBuilding = this.colourBuilding.bind(this);
+        this.increaseRevision = this.increaseRevision.bind(this);
+    }
+
+    componentWillReceiveProps(props: Readonly<MapAppProps>) {
+        const newCategory = this.getCategory(props.match.params.category);
+        if (newCategory != undefined) {
+            this.setState({ category: newCategory });
+        }
+    }
+
+    getCategory(category: string) {
+        if (category === 'categories') return undefined;
+
+        return category;
+    }
+
+    increaseRevision(revisionId) {
+        revisionId = +revisionId;
+        // bump revision id, only ever increasing
+        if (revisionId > this.state.revision_id) {
+            this.setState({ revision_id: revisionId })
+        }
+    }
+
+    selectBuilding(building) {
+        const mode = this.props.match.params.mode || 'view';
+        const category = this.props.match.params.category || 'age';
+
+        if (building == undefined || 
+            (this.state.building != undefined &&
+                building.building_id === this.state.building.building_id)) {
+            this.setState({ building: undefined });
+            this.props.history.push(`/${mode}/${category}`);
+            return;
+        }
+
+        this.increaseRevision(building.revision_id);
+        // get UPRNs and update
+        fetch(`/api/buildings/${building.building_id}/uprns.json`, {
+            method: 'GET',
+            headers: {
+                'Content-Type': 'application/json'
+            },
+            credentials: 'same-origin'
+        }).then(
+            res => res.json()
+        ).then((res) => {
+            if (res.error) {
+                console.error(res);
+            } else {
+                building.uprns = res.uprns;
+                this.setState({ building: building });
+            }
+        }).catch((err) => {
+            console.error(err)
+            this.setState({ building: building });
+        });
+
+        // get if liked and update
+        fetch(`/api/buildings/${building.building_id}/like.json`, {
+            method: 'GET',
+            headers: {
+                'Content-Type': 'application/json'
+            },
+            credentials: 'same-origin'
+        }).then(
+            res => res.json()
+        ).then((res) => {
+            if (res.error) {
+                console.error(res);
+            } else {
+                this.setState({ building_like: res.like });
+                this.props.history.push(`/${mode}/${category}/${building.building_id}`);
+            }
+        }).catch((err) => {
+            console.error(err)
+            this.setState({ building_like: false });
+        });
+    }
+
+    /**
+     * Colour building
+     *
+     * Used in multi-edit mode to colour buildings on map click
+     *
+     * Pulls data from URL to form update
+     *
+     * @param {object} building
+     */
+    colourBuilding(building) {
+        const cat = this.props.match.params.category;
+        const q = parse(window.location.search);
+        const data = (cat === 'like') ? { like: true } : JSON.parse(q.data as string); // TODO: verify what happens if data is string[]
+        if (cat === 'like') {
+            this.likeBuilding(building.building_id)
+        } else {
+            this.updateBuilding(building.building_id, data)
+        }
+    }
+
+    likeBuilding(buildingId) {
+        fetch(`/api/buildings/${buildingId}/like.json`, {
+            method: 'POST',
+            headers: {
+                'Content-Type': 'application/json'
+            },
+            credentials: 'same-origin',
+            body: JSON.stringify({ like: true })
+        }).then(
+            res => res.json()
+        ).then(function (res) {
+            if (res.error) {
+                console.error({ error: res.error })
+            } else {
+                this.increaseRevision(res.revision_id);
+            }
+        }.bind(this)).catch(
+            (err) => console.error({ error: err })
+        );
+    }
+
+    updateBuilding(buildingId, data) {
+        fetch(`/api/buildings/${buildingId}.json`, {
+            method: 'POST',
+            body: JSON.stringify(data),
+            headers: {
+                'Content-Type': 'application/json'
+            },
+            credentials: 'same-origin'
+        }).then(
+            res => res.json()
+        ).then(res => {
+            if (res.error) {
+                console.error({ error: res.error })
+            } else {
+                this.increaseRevision(res.revision_id);
+            }
+        }).catch(
+            (err) => console.error({ error: err })
+        );
+    }
+
+    render() {
+        const mode = this.props.match.params.mode || 'basic';
+
+        let category = this.state.category || 'age';
+
+        const building_id = this.state.building && this.state.building.building_id;
+
+        return (
+            <Fragment>
+                <Switch>
+                    <Route exact path="/">
+                        <Welcome />
+                    </Route>
+                    <Route exact path="/:mode/categories/:building?">
+                        <Sidebar>
+                            <Categories mode={mode} building_id={building_id} />
+                        </Sidebar>
+                    </Route>
+                    <Route exact path="/multi-edit/:cat" render={(props) => (
+                        <MultiEdit
+                            {...props}
+                            user={this.props.user}
+                        />
+                    )} />
+                    <Route exact path="/:mode/:cat/:building?">
+                        <Sidebar>
+                            <BuildingView
+                                mode={mode}
+                                cat={category}
+                                building={this.state.building}
+                                building_like={this.state.building_like}
+                                selectBuilding={this.selectBuilding}
+                                user={this.props.user}
+                            />
+                        </Sidebar>
+                    </Route>
+                    <Route exact path="/(view|edit|multi-edit)">
+                        <Redirect to="/view/categories" />
+                    </Route>
+                </Switch>
+                <ColouringMap
+                    building={this.state.building}
+                    mode={mode}
+                    category={category}
+                    revision_id={this.state.revision_id}
+                    selectBuilding={this.selectBuilding}
+                    colourBuilding={this.colourBuilding}
+                />
+            </Fragment>
+        );
+    }
+}
+
+export default MapApp;
\ No newline at end of file
diff --git a/app/src/frontend/map/map.tsx b/app/src/frontend/map/map.tsx
index 5b30d475..d606e622 100644
--- a/app/src/frontend/map/map.tsx
+++ b/app/src/frontend/map/map.tsx
@@ -14,6 +14,15 @@ import ThemeSwitcher from './theme-switcher';
 
 const OS_API_KEY = 'NVUxtY5r8eA6eIfwrPTAGKrAAsoeI9E9';
 
+interface ColouringMapProps {
+    building: any;
+    mode: 'basic' | 'view' | 'edit' | 'multi-edit';
+    category: string;
+    revision_id: number;
+    selectBuilding: any;
+    colourBuilding: any;
+}
+
 interface ColouringMapState {
     theme: 'light' | 'night';
     lat: number;
@@ -23,14 +32,14 @@ interface ColouringMapState {
 /**
  * Map area
  */
-class ColouringMap extends Component<any, ColouringMapState> { // TODO: add proper types
+class ColouringMap extends Component<ColouringMapProps, ColouringMapState> { // TODO: add proper types
     static propTypes = { // TODO: generate propTypes from TS
         building: PropTypes.object,
+        mode: PropTypes.string,
+        category: PropTypes.string,
         revision_id: PropTypes.number,
         selectBuilding: PropTypes.func,
-        colourBuilding: PropTypes.func,
-        match: PropTypes.object,
-        history: PropTypes.object
+        colourBuilding: PropTypes.func
     };
 
     constructor(props) {
@@ -44,7 +53,6 @@ class ColouringMap extends Component<any, ColouringMapState> { // TODO: add prop
         this.handleClick = this.handleClick.bind(this);
         this.handleLocate = this.handleLocate.bind(this);
         this.themeSwitch = this.themeSwitch.bind(this);
-        this.getMode = this.getMode.bind(this);
     }
 
     handleLocate(lat, lng, zoom){
@@ -52,21 +60,13 @@ class ColouringMap extends Component<any, ColouringMapState> { // TODO: add prop
             lat: lat,
             lng: lng,
             zoom: zoom
-        })
-    }
-
-    getMode() {
-        const isEdit = this.props.match.url.match('edit')
-        const isMulti = this.props.match.url.match('multi')
-        return isEdit? (isMulti? 'multi' : 'edit') : 'view';
+        });
     }
 
     handleClick(e) {
-        const mode = this.getMode()
-        const lat = e.latlng.lat
-        const lng = e.latlng.lng
-        const newCat = parseCategoryURL(this.props.match.url);
-        const mapCat = newCat || 'age';
+        const mode = this.props.mode;
+        const lat = e.latlng.lat;
+        const lng = e.latlng.lng;
         fetch(
             '/api/buildings/locate?lat='+lat+'&lng='+lng
         ).then(
@@ -74,17 +74,15 @@ class ColouringMap extends Component<any, ColouringMapState> { // TODO: add prop
         ).then(function(data){
             if (data && data.length){
                 const building = data[0];
-                if (mode === 'multi') {
+                if (mode === 'multi-edit') {
                     // colour building directly
                     this.props.colourBuilding(building);
                 } else {
                     this.props.selectBuilding(building);
-                    this.props.history.push(`/${mode}/${mapCat}/building/${building.building_id}.html`);
                 }
             } else {
                 // deselect but keep/return to expected colour theme
                 this.props.selectBuilding(undefined);
-                this.props.history.push(`/${mode}/${mapCat}.html`);
             }
         }.bind(this)).catch(
             (err) => console.error(err)
@@ -101,46 +99,49 @@ class ColouringMap extends Component<any, ColouringMapState> { // TODO: add prop
         const position: LatLngExpression = [this.state.lat, this.state.lng];
 
         // baselayer
-        const key = OS_API_KEY
-        const tilematrixSet = 'EPSG:3857'
+        const key = OS_API_KEY;
+        const tilematrixSet = 'EPSG:3857';
         const layer = (this.state.theme === 'light')? 'Light 3857' : 'Night 3857';
-        const url = `https://api2.ordnancesurvey.co.uk/mapping_api/v1/service/zxy/${tilematrixSet}/${layer}/{z}/{x}/{y}.png?key=${key}`
-        const attribution = 'Building attribute data is © Colouring London contributors. Maps contain OS data © Crown copyright: OS Maps baselayers and building outlines.'
+        const baseUrl = `https://api2.ordnancesurvey.co.uk/mapping_api/v1/service/zxy/${tilematrixSet}/${layer}/{z}/{x}/{y}.png?key=${key}`;
+        const attribution = 'Building attribute data is © Colouring London contributors. Maps contain OS data © Crown copyright: OS Maps baselayers and building outlines.';
+        const baseLayer = <TileLayer 
+            url={baseUrl}
+            attribution={attribution}
+        />;
+
+        const buildingsBaseUrl = `/tiles/base_${this.state.theme}/{z}/{x}/{y}.png`;
+        const buildingBaseLayer = <TileLayer url={buildingsBaseUrl} minZoom={14} />;
 
         // colour-data tiles
-        const isBuilding = /building/.test(this.props.match.url);
-        const isEdit = /edit/.test(this.props.match.url);
-        const cat = parseCategoryURL(this.props.match.url);
+        const cat = this.props.category;
         const tilesetByCat = {
             age: 'date_year',
             size: 'size_storeys',
             location: 'location',
             like: 'likes',
             planning: 'conservation_area',
-        }
+        };
         const tileset = tilesetByCat[cat];
         // pick revision id to bust browser cache
         const rev = this.props.revision_id;
-        const dataLayer = tileset?
+        const dataLayer = tileset != undefined ?
             <TileLayer
                 key={tileset}
                 url={`/tiles/${tileset}/{z}/{x}/{y}.png?rev=${rev}`}
-                minZoom={9} />
+                minZoom={9}
+            />
             : null;
 
         // highlight
-        const geometryId = (this.props.building) ? this.props.building.geometry_id : undefined;
-        const highlight = `/tiles/highlight/{z}/{x}/{y}.png?highlight=${geometryId}`
-        const highlightLayer = (isBuilding && this.props.building) ?
+        const highlightLayer = this.props.building != undefined ?
             <TileLayer
                 key={this.props.building.building_id}
-                url={highlight}
-                minZoom={14} />
+                url={`/tiles/highlight/{z}/{x}/{y}.png?highlight=${this.props.building.geometry_id}`}
+                minZoom={14} 
+            />
             : null;
 
-        const baseUrl = (this.state.theme === 'light')?
-            '/tiles/base_light/{z}/{x}/{y}.png'
-            : '/tiles/base_night/{z}/{x}/{y}.png'
+        const isEdit = ['edit', 'multi-edit'].includes(this.props.mode);
 
         return (
             <div className="map-container">
@@ -154,23 +155,23 @@ class ColouringMap extends Component<any, ColouringMapState> { // TODO: add prop
                     attributionControl={false}
                     onClick={this.handleClick}
                 >
-                    <TileLayer url={url} attribution={attribution} />
-                    <TileLayer url={baseUrl} minZoom={14} />
+                    { baseLayer }
+                    { buildingBaseLayer }
                     { dataLayer }
                     { highlightLayer }
                     <ZoomControl position="topright" />
-                    <AttributionControl prefix="" />
+                    <AttributionControl />
                 </Map>
                 {
-                    !isBuilding && this.props.match.url !== '/'? (
-                        <div className="map-notice">
-                            <HelpIcon /> {isEdit? 'Click a building to edit' : 'Click a building for details'}
-                        </div>
-                    ) : null
-                }
-                {
-                    this.props.match.url !== '/'? (
+                    this.props.mode !== 'basic'? (
                         <Fragment>
+                            {
+                                this.props.building == undefined ?
+                                    <div className="map-notice">
+                                        <HelpIcon /> {isEdit ? 'Click a building to edit' : 'Click a building for details'}
+                                    </div>
+                                    : null
+                            }
                             <Legend slug={cat} />
                             <ThemeSwitcher onSubmit={this.themeSwitch} currentTheme={this.state.theme} />
                             <SearchBox onLocate={this.handleLocate} />