// Create a base icon for all of our markers that specifies the
// shadow, icon dimensions, etc.
    var baseIcon = new GIcon();
    baseIcon.shadow = "http://www.google.com/mapfiles/shadow50.png";
    baseIcon.iconSize = new GSize(20, 34);
    baseIcon.shadowSize = new GSize(37, 34);
    baseIcon.iconAnchor = new GPoint(9, 34);
    baseIcon.infoWindowAnchor = new GPoint(9, 2);
    baseIcon.infoShadowAnchor = new GPoint(18, 25);

// Creates a marker whose info window displays the letter corresponding
// to the given index.
function createMarker(point, index, loc_title) {
  // Create a lettered icon for this point using our icon class
  var letter = String.fromCharCode("A".charCodeAt(0) + index);
  var letteredIcon = new GIcon(baseIcon);
  letteredIcon.image = "http://www.google.com/mapfiles/marker" + letter + ".png";

  // Set up our GMarkerOptions object
  markerOptions = { icon:letteredIcon };
  var marker = new GMarker(point, markerOptions);

  GEvent.addListener(marker, "click", function() {
    marker.openInfoWindowHtml(letter + ". " + loc_title);
  });
  return marker;
}