Get id of top level taxonomy

Hi there,

There is a simple issue that has been troubling me for quit some time now. On a Woocommerce product archive template I want to display the child categories of the top level category (which is a custom toxonomy actually).

I’ve nailed it almost, the only thing I need is to get the id of the top level taxonomy in a variable. Anyone?

This is what my code looks like.

<?php
        $taxonomy     = 'product_cat';
        $orderby      = 'name';
        $order        = 'DESC';
		$show_count   = 0;
        $pad_counts   = 0;
        $hierarchical = 1;

        $MY_TOP_LEVEL_ID = ?->term_id;

        $args2 = array(
          'taxonomy'     => $taxonomy,
          'child_of'     => $MY_TOP_LEVEL_ID,
          'show_count'   => $show_count,
          'pad_counts'   => $pad_counts,
          'hierarchical' => $hierarchical,
          'title_li'     => $title,
        );

        $sub_cats = get_categories( $args2 );

		$cat_id = get_query_var('cat');
		echo $cat_id;

		if (!empty($sub_cats)) { 

		echo '<ul class="categories">'; 

        foreach($sub_cats as $sub_category) {

	        if ($sub_cats->$sub_category == 0) {
	            $thumbnail_id  = get_woocommerce_term_meta( $sub_category->term_id, 'thumbnail_id', true );
	            $image = wp_get_attachment_url( $thumbnail_id );
				$name = $sub_category->name;
				$slug = $sub_category->slug;

	            echo '<li class="cat-item '.$slug.'"><a href="'. get_term_link($sub_category->slug, 'product_cat') .'"><img src="'.$image.'" " /><span class="txt">'.$name.'</span></a></li>';

	            }
	        }
			echo '<li class="cat-item search">';
			get_product_search_form();
			echo '</li>';

        echo '</ul>';

		 } //endif !empty ?>

Thanks!

[No bumping, thank you.]