Google Maps API: open url by clicking on marker

url isn't an object on the Marker class. But there's nothing stopping you adding that as a property to that class. I'm guessing whatever example you were looking at did that too. Do you want a different URL for each marker? What happens when you do:

for (var i = 0; i < locations.length; i++) 
{
    var flag = new google.maps.MarkerImage('markers/' + (i + 1) + '.png',
      new google.maps.Size(17, 19),
      new google.maps.Point(0,0),
      new google.maps.Point(0, 19));
    var place = locations[i];
    var myLatLng = new google.maps.LatLng(place[1], place[2]);
    var marker = new google.maps.Marker({
        position: myLatLng,
        map: map,
        icon: flag,
        shape: shape,
        title: place[0],
        zIndex: place[3],
        url: "/your/url/"
    });

    google.maps.event.addListener(marker, 'click', function() {
        window.location.href = this.url;
    });
}

You can add a specific url to each point, e.g.:

var points = [
    ['name1', 59.9362384705039, 30.19232525792222, 12, 'www.google.com'],
    ['name2', 59.941412822085645, 30.263564729357767, 11, 'www.amazon.com'],
    ['name3', 59.939177197629455, 30.273554411974955, 10, 'www.stackoverflow.com']
];

Add the url to the marker values in the for-loop:

var marker = new google.maps.Marker({
    ...
    zIndex: place[3],
    url: place[4]
});

Then you can add just before to the end of your for-loop:

google.maps.event.addListener(marker, 'click', function() {
    window.location.href = this.url;
});

Also see this example.

google.maps.event.addListener(marker, 'click', (function(marker, i) {
  return function() {
    window.location.href = marker.url;
  }
})(marker, i));