Update App.js

public/App.js

@@ -11,10 +11,9 @@
 		 animation: false,
 		 shadow: false,
 		 // // Set default basemap
-		 imageryProvider : Cesium.ArcGisMapServerImageryProvider({
-              url:
-                "https://services.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer"
-            }),        
+		 imageryProvider : Cesium.createOpenStreetMapImageryProvider({
+                            url : 'https://a.tile.openstreetmap.org/'
+                            }),        
 		 baseLayerPicker: true
 		 
      });