```html

    <link rel="stylesheet" href="http://libs.cartocdn.com/cartodb.js/v3/3.15/themes/css/cartodb.css" />
    <script src="http://libs.cartocdn.com/cartodb.js/v3/3.15/cartodb.js"></script>

    <!-- use these cartodb.css links if you are using https -->
    <!--link rel="stylesheet" href="https://cartodb-libs.global.ssl.fastly.net/cartodb.js/v3/3.15/themes/css/cartodb.css" /-->

    <!-- use this cartodb.js link if you are using https -->
    <!-- script src="https://cartodb-libs.global.ssl.fastly.net/cartodb.js/v3/3.15/cartodb.js"></script -->
```

```javascript
  var map = L.map('map').setView([0, 0], 3);

  // set a base layer
  L.tileLayer('http://a.tile.stamen.com/toner/{z}/{x}/{y}.png', {
    attribution: 'stamen http://maps.stamen.com/'
  }).addTo(map);

  // add the cartodb layer
  var layerUrl = 'http://documentation.cartodb.com/api/v2/viz/2b13c956-e7c1-11e2-806b-5404a6a683d5/viz.json';
  cartodb.createLayer(map, layerUrl).addTo(map);
```