https://snaprism.com/js/google-map/map-active.js

1var map;
2var latlng = new google.maps.LatLng(51.5074, 0.1278);
3var stylez = [{
4    featureType: "all",
5    elementType: "all",
6    stylers: [{
7        saturation: -100
8            }]
9        }];
10var mapOptions = {
11    zoom: 15,
12    center: latlng,
13    scrollwheel: false,
14    scaleControl: false,
15    disableDefaultUI: true,
16    mapTypeControlOptions: {
17        mapTypeIds: [google.maps.MapTypeId.ROADMAP, 'gMap']
18    }
19};
20map = new google.maps.Map(document.getElementById("googleMap"), mapOptions);
21var geocoder_map = new google.maps.Geocoder();
22var address = 'London';
23geocoder_map.geocode({
24    'address': address
25}, function (results, status) {
26    if (status == google.maps.GeocoderStatus.OK) {
27        map.setCenter(results[0].geometry.location);
28        var marker = new google.maps.Marker({
29            map: map,
30            icon: 'img/core-img/point.png',
31            position: map.getCenter()
32        });
33    } else {
34        alert("Geocode was not successful for the following reason: " + status);
35    }
36});
37var mapType = new google.maps.StyledMapType(stylez, {
38    name: "Grayscale"
39});
40map.mapTypes.set('gMap', mapType);
41map.setMapTypeId('gMap');