<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>
<!------ Include the above in your HEAD tag ---------->
<!DOCTYPE html>
<html>
<body>
<h1>My First Google Map</h1>
<div id="googleMap" style="width:100%;height:400px;"></div>
<script>
function myMap() {
var mapProp= {
center:new google.maps.LatLng(51.508742,-0.120850),
zoom:5,
};
var map = new google.maps.Map(document.getElementById("googleMap"),mapProp);
}
</script>
<script src="https://maps.googleapis.com/maps/api/js?key=YOUR_KEY&callback=myMap"></script>
</body>
</html>