diff --git a/example/index.js b/example/index.js
index 8fe1b89..0ff9458 100755
--- a/example/index.js
+++ b/example/index.js
@@ -41,7 +41,10 @@ define(['libraries/WebWorldWind/src/WorldWind', 'src/OSMBuildingLayer'],
     /* osmMilan.add();
     osmMilan.zoom(); */
     // var osmNewYork = new OSMBuildingLayer(worldWindow, [40.6998, -74.0232, 40.74, -73.97], configuration);
-    var osmNewYork = new OSMBuildingLayer(worldWindow, [40.70, -74.03, 40.72, -74.0], configuration);
-    osmNewYork.add();
+    var osmNewYork = new OSMBuildingLayer(worldWindow, configuration);
+    osmNewYork.addByBoundingBox([40.70, -74.03, 40.72, -74.0]);
     osmNewYork.zoom();
+    /* var osmMilan = new OSMBuildingLayer(worldWindow, [45.18, 9.48, 45.19, 9.53], configuration);
+    osmMilan.add();
+    osmMilan.zoom(); */
 });
diff --git a/src/GeoJSONParserTriangulation.js b/src/GeoJSONParserTriangulation.js
index 8dcc1b1..d490145 100644
--- a/src/GeoJSONParserTriangulation.js
+++ b/src/GeoJSONParserTriangulation.js
@@ -1,13 +1,12 @@
 /**
  * @exports GeoJSONParserTriangulation
  */
-define(['libraries/WebWorldWind/src/WorldWind',
-        'libraries/WebWorldWind/src/formats/geojson/GeoJSONParser',
+define(['libraries/WebWorldWind/src/formats/geojson/GeoJSONParser',
         'libraries/WebWorldWind/src/geom/Position',
         'libraries/WebWorldWind/src/shapes/TriangleMesh',
         'src/shapes/BuildingShape',
         'earcut'],
-       function (WorldWind, GeoJSONParser, Position, TriangleMesh, BuildingShape, earcut) {
+       function (GeoJSONParser, Position, TriangleMesh, BuildingShape, earcut) {
   "use strict";
 
   /**
diff --git a/src/GeoJSONParserTriangulationOSM.js b/src/GeoJSONParserTriangulationOSM.js
index 3c71d55..d805c8c 100644
--- a/src/GeoJSONParserTriangulationOSM.js
+++ b/src/GeoJSONParserTriangulationOSM.js
@@ -1,13 +1,9 @@
 /**
  * @exports GeoJSONParserTriangulationOSM
  */
-define(['libraries/WebWorldWind/src/WorldWind',
-        'libraries/WebWorldWind/src/geom/Position',
-        'libraries/WebWorldWind/src/shapes/TriangleMesh',
-        'src/GeoJSONParserTriangulation',
-        'src/shapes/BuildingShape',
-        'earcut'],
-       function (WorldWind, Position, TriangleMesh, GeoJSONParserTriangulation, BuildingShape, earcut) {
+define(['src/GeoJSONParserTriangulation',
+        'src/shapes/BuildingShape'],
+       function (GeoJSONParserTriangulation, BuildingShape) {
   "use strict";
 
   /**
diff --git a/src/OSMBuildingLayer.js b/src/OSMBuildingLayer.js
index c89aa36..67f6dd2 100644
--- a/src/OSMBuildingLayer.js
+++ b/src/OSMBuildingLayer.js
@@ -1,13 +1,12 @@
 /**
  * @exports OSMBuildingLayer
  */
-define(['libraries/WebWorldWind/src/WorldWind',
-        'libraries/WebWorldWind/src/cache/MemoryCache',
+define(['libraries/WebWorldWind/src/cache/MemoryCache',
         'src/OSMLayer',
         'src/GeoJSONParserTriangulationOSM',
         'jquery',
         'osmtogeojson'],
-       function (WorldWind, MemoryCache, OSMLayer, GeoJSONParserTriangulationOSM, $, osmtogeojson) {
+       function (MemoryCache, OSMLayer, GeoJSONParserTriangulationOSM, $, osmtogeojson) {
   "use strict";
 
   /**
@@ -16,11 +15,10 @@ define(['libraries/WebWorldWind/src/WorldWind',
    * @constructor
    * @classdesc Fetches OSM buildings, converts them to GeoJSON, and adds them to the WorldWindow.
    * @param {WorldWindow} worldWindow The WorldWindow where the OSMBuildingLayer is added to.
-   * @param {Float[]} boundingBox It defines the bounding box of the OSM data for the OSMLayer. The order of coordinates of the bounding box is "x1, y1, x2, y2".
    * @param {Object} configuration Configuration is used to set the attributes of {@link ShapeAttributes}. Four more attributes can be defined, which are "extrude", "heatmap", "altitude" and "altitudeMode".
    */
-  var OSMBuildingLayer = function (worldWindow, boundingBox, configuration) {
-    OSMLayer.call(this, worldWindow, boundingBox, configuration);
+  var OSMBuildingLayer = function (worldWindow, configuration) {
+    OSMLayer.call(this, worldWindow, configuration);
     this.type = "way";
     this.tag = "building";
     this._geometryCache = new MemoryCache(30000, 24000);
@@ -95,13 +93,17 @@ define(['libraries/WebWorldWind/src/WorldWind',
   };
 
   /**
-   * Using the boundingBox of the OSMBuildingLayer, fetches the OSM building data using Overpass API, converts it to GeoJSON using osmtogeojson API,
-   * adds the GeoJSON data to the WorldWindow using the {@link GeoJSONParserTriangulationOSM}.
+   * Using the boundingBox fetches the OSM building data using Overpass API, converts it to GeoJSON using osmtogeojson API,
+   * adds the GeoJSON to the WorldWindow using the {@link GeoJSONParserTriangulationOSM}.
+   * It also sets the boundingBox of the {@link OSMLayer}.
+   * @param {Float[]} boundingBox It defines the bounding box of the OSM data to add.
    */
-  OSMBuildingLayer.prototype.add = function () {
+  OSMBuildingLayer.prototype.addByBoundingBox = function (boundingBox) {
 
-    var boundingBox = this.boundingBox;
+    this.boundingBox = boundingBox;
     var worldWindow = this.worldWindow;
+    /* var dc = this.worldWindow.drawContext;
+    console.log("dc.globe --> " + dc.globe); */
     var _self = this;
 
     var data = '[out:json][timeout:25];';
@@ -138,5 +140,19 @@ define(['libraries/WebWorldWind/src/WorldWind',
     });
   };
 
+  /**
+   *
+   */
+  OSMBuildingLayer.prototype.addByFile = function (path) {
+
+  };
+
+  /**
+   *
+   */
+  OSMBuildingLayer.prototype.addByURL = function (path) {
+
+  };
+
   return OSMBuildingLayer;
 });
diff --git a/src/OSMLayer.js b/src/OSMLayer.js
index bd98ad7..1da4b46 100644
--- a/src/OSMLayer.js
+++ b/src/OSMLayer.js
@@ -1,7 +1,9 @@
 /**
  * @exports OSMLayer
  */
-define(['libraries/WebWorldWind/src/WorldWind'], function (WorldWind) {
+define(['libraries/WebWorldWind/src/error/ArgumentError',
+        'libraries/WebWorldWind/src/util/Logger'],
+       function (ArgumentError, Logger) {
   "use strict";
 
   /**
@@ -10,13 +12,12 @@ define(['libraries/WebWorldWind/src/WorldWind'], function (WorldWind) {
    * @constructor
    * @classdesc Sets the properties and functions viable for any OSM data. It is intended to be an abstract class, only to be extended for specific OSM data.
    * @param {WorldWindow} worldWindow The WorldWindow where the OSMLayer is added to.
-   * @param {Float[]} boundingBox It defines the bounding box of the OSM data for the OSMLayer.
    * @param {Object} configuration Configuration is used to set the attributes of {@link PlacemarkAttributes} or {@link ShapeAttributes}.
    */
-  var OSMLayer = function (worldWindow, boundingBox, configuration) {
+  var OSMLayer = function (worldWindow, configuration) {
     this._worldWindow = worldWindow;
-    this._boundingBox = boundingBox;
     this._configuration = configuration;
+    this._boundingBox = null;
     this._type = null;
     this._tag = null;
   };
@@ -33,17 +34,6 @@ define(['libraries/WebWorldWind/src/WorldWind'], function (WorldWind) {
         return this._worldWindow;
       }
     },
-    /**
-     * It defines the bounding box of the OSM data for the OSMLayer. The order of coordinates of the bounding box is "x1, y1, x2, y2".
-     * @memberof OSMLayer.prototype
-     * @type {Float[]}
-     * @readonly
-     */
-    boundingBox: {
-      get: function() {
-        return this._boundingBox;
-      }
-    },
     /**
      * Configuration is used to set the attributes of {@link PlacemarkAttributes} if the geometry is Point or MultiPoint; or of {@link ShapeAttributes} otherwise.
      * @memberof OSMLayer.prototype
@@ -57,6 +47,19 @@ define(['libraries/WebWorldWind/src/WorldWind'], function (WorldWind) {
         this._configuration = configuration;
       }
     },
+    /**
+     * It defines the bounding box of the OSM data for the OSMLayer. The order of coordinates of the bounding box is "x1, y1, x2, y2".
+     * @memberof OSMLayer.prototype
+     * @type {Float[]}
+     */
+    boundingBox: {
+      get: function() {
+        return this._boundingBox;
+      },
+      set: function(boundingBox) {
+        this._boundingBox = boundingBox;
+      }
+    },
     /**
      * The type of the OSM data. It can be "node", "way", or "relation".
      * @memberof OSMLayer.prototype
@@ -113,16 +116,24 @@ define(['libraries/WebWorldWind/src/WorldWind'], function (WorldWind) {
   /**
    * Zooms to the OSMLayer, by setting the center of the viewport to the center of the bounding box.
    * It uses an arbitrary value for the range of {@link LookAtNavigator}.
+   * @throws {ArgumentError} If boundingBox of the layer is null.
    */
   OSMLayer.prototype.zoom = function () {
-    var boundingBox = this.boundingBox;
-    var centerX = (boundingBox[0] + boundingBox[2])/2;
-    var centerY = (boundingBox[1] + boundingBox[3])/2;
-    this.worldWindow.navigator.lookAtLocation.latitude = centerX;
-    this.worldWindow.navigator.lookAtLocation.longitude = centerY;
-    // console.log(centerX + ", " + centerY);
-    this.worldWindow.navigator.range = 1e4; // Should be automatically calculated.
-    this.worldWindow.redraw();
+    if (this.boundingBox != null) {
+      var boundingBox = this.boundingBox;
+      var centerX = (boundingBox[0] + boundingBox[2])/2;
+      var centerY = (boundingBox[1] + boundingBox[3])/2;
+      this.worldWindow.navigator.lookAtLocation.latitude = centerX;
+      this.worldWindow.navigator.lookAtLocation.longitude = centerY;
+      // console.log(centerX + ", " + centerY);
+      this.worldWindow.navigator.range = 1e4; // Should be automatically calculated.
+      this.worldWindow.redraw();
+    }
+    else {
+      throw new ArgumentError(
+        Logger.logMessage(Logger.LEVEL_SEVERE, "OSMLayer", "zoom", "The bounding box of the layer is null.")
+      );
+    }
   };
 
   return OSMLayer;