function initialize() {
  var myOptions = {
    zoom: 15,
    center: new google.maps.LatLng(39.16555517756163, -75.53192853927612),
    mapTypeId: google.maps.MapTypeId.ROADMAP
  }
  var map = new google.maps.Map(document.getElementById("map_canvas"),
                                myOptions);
 
  setMarkers(map, schools);
}
 
/**
 * Data for the markers consisting of a name, a LatLng and a zIndex for
 * the order in which these markers should display on top of each
 * other.
 */
var schools = [
  ['HS', 39.16555517756163, -75.53688526153564, 2],
  ['ES', 39.16186174322811, -75.526864528656, 1],
];
 
function setMarkers(map, locations) {
  // Add markers to the map
 
  // Marker sizes are expressed as a Size of X,Y
  // where the origin of the image (0,0) is located
  // in the top left of the image.
 
  // Origins, anchor positions and coordinates of the marker
  // increase in the X direction to the right and in
  // the Y direction down.
  var image = new google.maps.MarkerImage('/images/map-icon.png',
      // This marker is 20 pixels wide by 32 pixels tall.
      new google.maps.Size(150, 100),
      // The origin for this image is 0,0.
      new google.maps.Point(0,0),
      // The anchor for this image is the base of the flagpole at 0,32.
      new google.maps.Point(74, 100));
  var shadow = new google.maps.MarkerImage('images/beachflag_shadow.png',
      // The shadow image is larger in the horizontal dimension
      // while the position and offset are the same as for the main image.
      new google.maps.Size(37, 32),
      new google.maps.Point(0,0),
      new google.maps.Point(0, 32));
      // Shapes define the clickable region of the icon.
      // The type defines an HTML <area> element 'poly' which
      // traces out a polygon as a series of X,Y points. The final
      // coordinate closes the poly by connecting to the first
      // coordinate.
  var shape = {
      coord: [1, 1, 1, 20, 18, 20, 18 , 1],
      type: 'poly'
  };
  for (var i = 0; i < locations.length; i++) {
    var beach = locations[i];
    var myLatLng = new google.maps.LatLng(beach[1], beach[2]);
    var marker = new google.maps.Marker({
        position: myLatLng,
        map: map,
        shadow: shadow,
        icon: image,
        shape: shape,
        title: beach[0],
        zIndex: beach[3]
    });
  }
}