<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script src="//code.jquery.com/jquery-3.3.1.min.js"></script>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/gh/fancyapps/fancybox@3.5.7/dist/jquery.fancybox.min.css" />
<script src="https://cdn.jsdelivr.net/gh/fancyapps/fancybox@3.5.7/dist/jquery.fancybox.min.js"></script>
<div class="container">
<div class="row">
<a data-fancybox="gallery" href="big_1.jpg"><img src="https://images.pexels.com/photos/2108932/pexels-photo-2108932.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=650&w=940"></a>
<a data-fancybox="gallery" href="big_2.jpg"><img src="https://images.pexels.com/photos/2115578/pexels-photo-2115578.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=650&w=940"></a>
</div>
</div>