private static ESRI.ArcGIS.Client.Projection.WebMercator _mercator = new ESRI.ArcGIS.Client.Projection.WebMercator(); GraphicsLayer _locationGraphicsLayer; public LocationToAddress() { InitializeComponent(); ESRI.ArcGIS.Client.Geometry.Envelope initialExtent = new ESRI.ArcGIS.Client.Geometry.Envelope( _mercator.FromGeographic( new ESRI.ArcGIS.Client.Geometry.MapPoint(-117.387, 33.97)) as MapPoint, _mercator.FromGeographic( new ESRI.ArcGIS.Client.Geometry.MapPoint(-117.355, 33.988)) as MapPoint); initialExtent.SpatialReference = new SpatialReference(3857); MyMap.Extent = initialExtent; _locationGraphicsLayer = MyMap.Layers["LocationGraphicsLayer"] as GraphicsLayer; }