post_thumbnail url custom loop

<?php
    $args = array( 'post_type' => 'work' );
    $go = new WP_Query( $args );
    while ( $go->have_posts() ) : $go->the_post();
?>
<?php
    $imgID = get_post_thumbnail_id();
    $url = wp_get_attachment_url( get_post_thumbnail_id($post->ID) );
?>
<article class="work">
    <a class="group" rel="fancybox" href="<?php echo $url; ?>" >
        <div class="work-thumb">
            <?php the_post_thumbnail(); ?>
        </div>
        <h4 class="work-info work-title">
            <?php the_title(); ?>
        </h4>
        <div class="work-info work-content">
            <?php the_content(); ?>
        </div>
    </a>
</article>
<?php endwhile; wp_reset_query(); ?>