Wordpress get menu list by menu name

<?php
$menu_items = wp_get_nav_menu_items('city');
echo "<pre>";
print_r($menu_items);
?>
<select onChange="document.location.href=this[selectedIndex].value">
    <option value="<?php bloginfo('url'); ?>">-select-</option>
    <?php foreach($menu_items as $item){ ?>
    <option value="<?php echo $item->url; ?>"><?php echo $item->title; ?></option>
      <?php }?>
</select>