gistfile1.php

<?php
$c = (new MongoClient())->demo->points;

$c->find( [
    'loc' => [
        '$geoWithin' => [
            'type' => 'Polygon',
            'coordinates' => [ [
                [ -0.91, 51.74 ],
                [ -0.91, 51.27 ],
                [  0.67, 51.27 ],
                [  0.67, 51.74 ],
                [ -0.91, 51.74 ]
            ] ]
        ]
    ]
] );
?>