diff --git a/pxy_dashboard/templates/pxy_dashboard/apps/apps-sites-viewer.html b/pxy_dashboard/templates/pxy_dashboard/apps/apps-sites-viewer.html
index f50d16a..80ffa6f 100644
--- a/pxy_dashboard/templates/pxy_dashboard/apps/apps-sites-viewer.html
+++ b/pxy_dashboard/templates/pxy_dashboard/apps/apps-sites-viewer.html
@@ -4,10 +4,12 @@
 {% block title %}Sites · Run viewer{% endblock title %}
 
 {% block extra_css %}
-<link rel="stylesheet" href="https://unpkg.com/leaflet@1.9.4/dist/leaflet.css"
-  integrity="sha256-p4NxAoJBhIIN+hmNHrzRCf9tD/miZyoHS5obTRR9BMY=" crossorigin="">
+<link
+  rel="stylesheet"
+  href="https://cesium.com/downloads/cesiumjs/releases/1.114/Build/Cesium/Widgets/widgets.css"
+/>
 <style>
-  #sites-map { height: 70vh; border-radius: 0.5rem; }
+  #sites-map { height: 70vh; border-radius: 0.5rem; overflow: hidden; }
   .layer-chip { margin-right: .75rem; }
   .leaflet-popup-content { margin: 10px 14px; }
   .scrub-wrap { display:flex; align-items:center; gap:.5rem; }
@@ -69,6 +71,15 @@
                 <label class="form-check-label" for="chkComp">Competition (sample)</label>
               </div>
             </div>
+            <div class="d-flex align-items-center">
+              <label class="me-2">Basemap</label>
+              <select id="basemap" class="form-select form-select-sm" style="min-width: 180px;">
+                <option value="osm">OpenStreetMap</option>
+                <option value="esri">ESRI World Imagery</option>
+                <option value="carto_light">CARTO Light</option>
+                <option value="carto_dark">CARTO Dark</option>
+              </select>
+            </div>
           </div>
         </div>
 
@@ -80,7 +91,7 @@
         </div>
 
         <div class="text-muted small mt-1">
-          Tip: hover candidates for score & breakdown; toggle layers on the right; use the scrubber to switch minutes.
+          Tip: click candidates for score & breakdown; toggle layers on the right; use the scrubber to switch minutes.
         </div>
       </div>
     </div>
@@ -89,8 +100,7 @@
 {% endblock content %}
 
 {% block extra_js %}
-<script src="https://unpkg.com/leaflet@1.9.4/dist/leaflet.js"
-  integrity="sha256-20nQCchB9co0qIjJZRGuk2/Z9VM+kNiyxNV1lvTlZBo=" crossorigin=""></script>
+<script src="https://cesium.com/downloads/cesiumjs/releases/1.114/Build/Cesium/Cesium.js"></script>
 <script>
 (function(){
   const q = new URLSearchParams(window.location.search);
@@ -113,23 +123,93 @@
     return;
   }
 
-  // Base map
-  const map = L.map('sites-map', { zoomControl: true });
-  L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png',
-    { maxZoom: 19, attribution: '&copy; OpenStreetMap' }).addTo(map);
+  const viewer = new Cesium.Viewer('sites-map', {
+    imageryProvider: false,
+    baseLayerPicker: false,
+    geocoder: false,
+    homeButton: false,
+    navigationHelpButton: false,
+    sceneModePicker: false,
+    animation: false,
+    timeline: false,
+    infoBox: true,
+    selectionIndicator: true,
+  });
+
+  const basemapSelect = document.getElementById('basemap');
+  const basemapLayers = {};
+
+  function getBasemapProvider(key) {
+    if (key === 'osm') {
+      return new Cesium.OpenStreetMapImageryProvider({
+        url: 'https://tile.openstreetmap.org/',
+      });
+    }
+    if (key === 'esri') {
+      return new Cesium.UrlTemplateImageryProvider({
+        url: 'https://services.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/tile/{z}/{y}/{x}',
+        credit: 'Esri',
+      });
+    }
+    if (key === 'carto_light') {
+      return new Cesium.UrlTemplateImageryProvider({
+        url: 'https://cartodb-basemaps-a.global.ssl.fastly.net/light_all/{z}/{x}/{y}.png',
+        credit: 'CARTO',
+      });
+    }
+    if (key === 'carto_dark') {
+      return new Cesium.UrlTemplateImageryProvider({
+        url: 'https://cartodb-basemaps-a.global.ssl.fastly.net/dark_all/{z}/{x}/{y}.png',
+        credit: 'CARTO',
+      });
+    }
+    return null;
+  }
+
+  function setBaseLayer(key) {
+    let layer = basemapLayers[key];
+    if (!layer) {
+      const provider = getBasemapProvider(key);
+      if (!provider) {
+        return;
+      }
+      layer = viewer.imageryLayers.addImageryProvider(provider);
+      basemapLayers[key] = layer;
+    }
+    Object.keys(basemapLayers).forEach((k) => {
+      basemapLayers[k].show = k === key;
+    });
+    viewer.imageryLayers.raiseToTop(layer);
+  }
+
+  basemapSelect.addEventListener('change', () => {
+    setBaseLayer(basemapSelect.value);
+  });
+  setBaseLayer(basemapSelect.value);
+
+  viewer.scene.globe.depthTestAgainstTerrain = false;
 
-  // Layers
   const layers = {
-    iso: L.layerGroup().addTo(map),
-    cand: L.layerGroup().addTo(map),
-    demand: L.layerGroup(),
-    comp: L.layerGroup(),
+    iso: new Map(),
+    cand: null,
+    demand: null,
+    comp: null,
   };
-  document.getElementById('chkIso').addEventListener('change', (e)=> toggle(layers.iso, e.target.checked));
-  document.getElementById('chkCand').addEventListener('change', (e)=> toggle(layers.cand, e.target.checked));
-  document.getElementById('chkDemand').addEventListener('change', (e)=> toggle(layers.demand, e.target.checked));
-  document.getElementById('chkComp').addEventListener('change', (e)=> toggle(layers.comp, e.target.checked));
-  function toggle(layer, on){ if (on) layer.addTo(map); else map.removeLayer(layer); }
+
+  let isoVisible = true;
+  document.getElementById('chkIso').addEventListener('change', (e)=> {
+    isoVisible = e.target.checked;
+    renderMinute(currentIndex);
+  });
+  document.getElementById('chkCand').addEventListener('change', (e)=> {
+    if (layers.cand) layers.cand.show = e.target.checked;
+  });
+  document.getElementById('chkDemand').addEventListener('change', (e)=> {
+    if (layers.demand) layers.demand.show = e.target.checked;
+  });
+  document.getElementById('chkComp').addEventListener('change', (e)=> {
+    if (layers.comp) layers.comp.show = e.target.checked;
+  });
 
   const isoURL   = `/api/sites/geojson/isochrones/${encodeURIComponent(sid)}`;
   const candURL  = `/api/sites/geojson/candidates/${encodeURIComponent(sid)}`;
@@ -137,12 +217,10 @@
   const compURL  = `/api/sites/geojson/pois_competition/${encodeURIComponent(sid)}`;
   const artURL   = `/media/sites/run_${encodeURIComponent(sid)}.json`;
 
-  let fitBounds = null;
-
   // 55A scrubber state
   const bandColors = ['#2E86AB','#F18F01','#C73E1D','#6C5B7B','#17B890','#7E57C2'];
   let minutes = [];
-  const isoGroups = new Map();    // minute -> LayerGroup
+  const isoGroups = new Map();    // minute -> array of features
   const minuteAreas = new Map();  // minute -> total area_km2
   let currentIndex = 0;
   let timer = null;
@@ -162,14 +240,13 @@
   function renderMinute(idx) {
     currentIndex = Math.max(0, Math.min(idx, minutes.length - 1));
     const m = minutes[currentIndex];
-    minuteText.textContent = `${m} min`;
+    minuteText.textContent = m != null ? `${m} min` : '—';
     areaText.textContent = fmtArea(minuteAreas.get(m));
 
-    layers.iso.clearLayers();
-    const group = isoGroups.get(m);
-    if (group) layers.iso.addLayer(group);
+    layers.iso.forEach((ds, minute)=>{
+      ds.show = isoVisible && minute === m;
+    });
 
-    // 55B: move chart marker
     updateAreaMarker(m);
   }
 
@@ -274,7 +351,7 @@
 
   function updateAreaMarker(minute) {
     if (!chartState) return;
-    const { mins, areas, x, y, padT, H } = chartState;
+    const { mins, areas, x, y } = chartState;
     const i = Math.max(0, mins.indexOf(minute));
     const X = x(mins[i]);
     const Y = y(areas[i]);
@@ -285,6 +362,51 @@
     if (dot)  { dot.setAttribute('cx', X); dot.setAttribute('cy', Y); }
   }
 
+  function extendBounds(bounds, lon, lat) {
+    if (!bounds) {
+      return { minLon: lon, minLat: lat, maxLon: lon, maxLat: lat };
+    }
+    return {
+      minLon: Math.min(bounds.minLon, lon),
+      minLat: Math.min(bounds.minLat, lat),
+      maxLon: Math.max(bounds.maxLon, lon),
+      maxLat: Math.max(bounds.maxLat, lat),
+    };
+  }
+
+  function boundsFromGeometry(bounds, geom) {
+    if (!geom) return bounds;
+    if (geom.type === 'Point') {
+      return extendBounds(bounds, geom.coordinates[0], geom.coordinates[1]);
+    }
+    if (geom.type === 'Polygon') {
+      geom.coordinates.forEach(ring => {
+        ring.forEach(coord => { bounds = extendBounds(bounds, coord[0], coord[1]); });
+      });
+    }
+    if (geom.type === 'MultiPolygon') {
+      geom.coordinates.forEach(poly => {
+        poly.forEach(ring => {
+          ring.forEach(coord => { bounds = extendBounds(bounds, coord[0], coord[1]); });
+        });
+      });
+    }
+    return bounds;
+  }
+
+  function flyToBounds(bounds) {
+    if (!bounds) return;
+    const rect = Cesium.Rectangle.fromDegrees(bounds.minLon, bounds.minLat, bounds.maxLon, bounds.maxLat);
+    viewer.camera.flyTo({ destination: rect });
+  }
+
+  async function loadGeoJson(fc, options) {
+    if (!fc || !fc.features || fc.features.length === 0) {
+      return null;
+    }
+    return Cesium.GeoJsonDataSource.load(fc, options);
+  }
+
   // Fetch everything
   Promise.allSettled([
     fetch(isoURL).then(r=>r.ok?r.json():null),
@@ -292,32 +414,45 @@
     fetch(demURL).then(r=>r.ok?r.json():null),
     fetch(compURL).then(r=>r.ok?r.json():null),
     fetch(artURL).then(r=>r.ok?r.json():null)
-  ]).then(([iso, cand, dem, comp, art])=>{
+  ]).then(async ([iso, cand, dem, comp, art])=>{
     const isoFC  = iso.value || {type:'FeatureCollection',features:[]};
     const candFC = cand.value|| {type:'FeatureCollection',features:[]};
     const demFC  = dem.value || {type:'FeatureCollection',features:[]};
     const compFC = comp.value|| {type:'FeatureCollection',features:[]};
     const artObj = art.value || null;
 
-    // Fit bounds to all isochrones
-    const allIso = L.geoJSON(isoFC);
-    const b = allIso.getBounds();
-    if (b.isValid()) { map.fitBounds(b.pad(0.05)); fitBounds = b; }
+    let bounds = null;
 
     // Build minute groups + areas
     (isoFC.features || []).forEach((f)=>{
       const m = (f.properties && Number(f.properties.minutes)) || 0;
-      if (!isoGroups.has(m)) isoGroups.set(m, L.layerGroup());
-      const i = Math.max(0, Math.floor(m/5) - 1);
-      const c = bandColors[i % bandColors.length];
-      const lyr = L.geoJSON(f, { style: { color:c, weight:2, fillColor:c, fillOpacity:.25 } });
-      isoGroups.get(m).addLayer(lyr);
+      if (!isoGroups.has(m)) isoGroups.set(m, []);
+      isoGroups.get(m).push(f);
       const a = Number((f.properties && f.properties.area_km2) || 0);
       minuteAreas.set(m, (minuteAreas.get(m) || 0) + (isFinite(a) ? a : 0));
+      bounds = boundsFromGeometry(bounds, f.geometry);
     });
 
     minutes = Array.from(isoGroups.keys()).sort((a,b)=>a-b);
 
+    for (const minute of minutes) {
+      const i = Math.max(0, Math.floor(minute/5) - 1);
+      const colorHex = bandColors[i % bandColors.length];
+      const color = Cesium.Color.fromCssColorString(colorHex);
+      const fc = { type: 'FeatureCollection', features: isoGroups.get(minute) || [] };
+      const ds = await loadGeoJson(fc, {
+        stroke: color,
+        fill: color.withAlpha(0.25),
+        strokeWidth: 2,
+        clampToGround: true,
+      });
+      if (ds) {
+        ds.show = false;
+        viewer.dataSources.add(ds);
+        layers.iso.set(minute, ds);
+      }
+    }
+
     // 55B: draw chart if ≥2 bands
     if (minutes.length >= 2) {
       const areas = minutes.map(m => minuteAreas.get(m) || 0);
@@ -340,49 +475,75 @@
     }
 
     // Candidates
-    L.geoJSON(candFC, {
-      pointToLayer: (f, latlng)=>{
-        const s = Number(f.properties?.score ?? 0.5);
-        const r = 6 + Math.round(s * 10);
-        return L.circleMarker(latlng, { radius: r, weight: 2, color: '#111', fillOpacity: 0.9 });
-      },
-      onEachFeature: (f, layer)=>{
-        const p = f.properties || {};
-        const score = Number(p.score ?? 0).toFixed(2);
-        const br = `Demand ${Number(p.demand||0).toFixed(2)}, `
-                 + `Comp ${Number(p.competition||0).toFixed(2)}, `
-                 + `Access ${Number(p.access||0).toFixed(2)}`;
-        layer.bindPopup(`<b>Rank ${p.rank || '—'}</b> · score ${score}<br><small>${br}</small>`);
+    layers.cand = await loadGeoJson(candFC, { clampToGround: true });
+    if (layers.cand) {
+      viewer.dataSources.add(layers.cand);
+      layers.cand.entities.values.forEach((entity)=>{
+        const score = entity.properties?.score?.getValue(Cesium.JulianDate.now()) || 0;
+        const rank = entity.properties?.rank?.getValue(Cesium.JulianDate.now()) || '—';
+        const demand = entity.properties?.demand?.getValue(Cesium.JulianDate.now()) || 0;
+        const competition = entity.properties?.competition?.getValue(Cesium.JulianDate.now()) || 0;
+        const access = entity.properties?.access?.getValue(Cesium.JulianDate.now()) || 0;
+        const radius = 6 + Math.round(score * 10);
+        entity.point = new Cesium.PointGraphics({
+          pixelSize: radius,
+          color: Cesium.Color.fromCssColorString('#1B998B'),
+          outlineColor: Cesium.Color.BLACK.withAlpha(0.7),
+          outlineWidth: 1,
+        });
+        entity.description = `<b>Rank ${rank}</b> · score ${Number(score).toFixed(2)}<br>` +
+          `<small>Demand ${Number(demand).toFixed(2)}, ` +
+          `Comp ${Number(competition).toFixed(2)}, ` +
+          `Access ${Number(access).toFixed(2)}</small>`;
+      });
+      if (!bounds) {
+        candFC.features.forEach((f)=>{ bounds = boundsFromGeometry(bounds, f.geometry); });
       }
-    }).addTo(layers.cand);
-
-    if (!fitBounds) {
-      const b2 = L.geoJSON(candFC).getBounds();
-      if (b2.isValid()) map.fitBounds(b2.pad(0.1));
-      else map.setView([19.4326, -99.1332], 11);
     }
 
     // Demand & Competition (start hidden)
-    L.geoJSON(demFC, {
-      pointToLayer: (f, latlng)=> L.circleMarker(latlng, { radius: 3, color: '#d9534f', weight: 0, fillOpacity: .7 }),
-      onEachFeature: (f, layer)=>{
-        const pop = f.properties?.pop;
-        if (pop) layer.bindPopup(`Population: ${Math.round(pop)}`);
-      }
-    }).addTo(layers.demand);
-    L.geoJSON(compFC, {
-      pointToLayer: (f, latlng)=> L.circleMarker(latlng, { radius: 3, color: '#0d6efd', weight: 0, fillOpacity: .7 }),
-      onEachFeature: (f, layer)=>{
-        const name = f.properties?.name || '(poi)';
-        const cat  = f.properties?.category || '';
-        layer.bindPopup(`${name}${cat?' — '+cat:''}`);
-      }
-    }).addTo(layers.comp);
-    map.removeLayer(layers.demand);
-    map.removeLayer(layers.comp);
+    layers.demand = await loadGeoJson(demFC, { clampToGround: true });
+    if (layers.demand) {
+      viewer.dataSources.add(layers.demand);
+      layers.demand.show = false;
+      layers.demand.entities.values.forEach((entity)=>{
+        entity.point = new Cesium.PointGraphics({
+          pixelSize: 4,
+          color: Cesium.Color.fromCssColorString('#d9534f'),
+          outlineColor: Cesium.Color.BLACK.withAlpha(0.4),
+          outlineWidth: 1,
+        });
+      });
+    }
+
+    layers.comp = await loadGeoJson(compFC, { clampToGround: true });
+    if (layers.comp) {
+      viewer.dataSources.add(layers.comp);
+      layers.comp.show = false;
+      layers.comp.entities.values.forEach((entity)=>{
+        const name = entity.properties?.name?.getValue(Cesium.JulianDate.now()) || '(poi)';
+        const cat = entity.properties?.category?.getValue(Cesium.JulianDate.now()) || '';
+        entity.point = new Cesium.PointGraphics({
+          pixelSize: 4,
+          color: Cesium.Color.fromCssColorString('#0d6efd'),
+          outlineColor: Cesium.Color.BLACK.withAlpha(0.4),
+          outlineWidth: 1,
+        });
+        entity.description = `${name}${cat ? ' — ' + cat : ''}`;
+      });
+    }
+
     document.getElementById('chkDemand').checked = false;
     document.getElementById('chkComp').checked = false;
 
+    if (bounds) {
+      flyToBounds(bounds);
+    } else {
+      viewer.camera.flyTo({
+        destination: Cesium.Cartesian3.fromDegrees(-99.1332, 19.4326, 14000),
+      });
+    }
+
     // Meta (best-effort via artifact)
     if (artObj && artObj.request) {
       const req = artObj.request;
@@ -397,7 +558,7 @@
   let _rt = null;
   window.addEventListener('resize', ()=>{
     if (!_rt) {
-      _rt = requestAnimationFrame(()=>{ 
+      _rt = requestAnimationFrame(()=>{
         if (minutes.length >= 2) {
           const areas = minutes.map(m => minuteAreas.get(m) || 0);
           drawAreaChart(minutes, areas);