Wordpress - Retrieve all Posts by 'post_type' then filter by taxonomy

I have a Wordpress installation with ACF (Advanced Custom Fields) installed. I created the Class post type and each Class has it's on Location value.
How can I retrieve every Class and get the location I have chosen for that Class? I'm currently using this function to retrieve the name of the 'Programs':

<pre>
    $args = array(
        'post_type' => 'class',
        'posts_per_page' => -1,
    );
    $query = new WP_Query($args);
    if ($query->have_posts() ) : 
        while ( $query->have_posts() ) : $query->the_post();
            echo get_the_ID();
            echo get_the_title();
        endwhile;
    endif;
</pre>

I'm trying to populate a dropdown list 'Location' which filters the next dropdown with the classes available for that location.
Any help or advice would be greatly appreciated. Thanks