Create a Navigation "loop" by generating the URL

I’m trying to create a navigation where the last post links to the first post in my portfolio site so that there is a continuous loop.

I had some success with the Loop Post Navigation plugin, but the problem is I can’t get the plugin to generate only a URL.

Here’s the closest I’ve gotten so far to using URLs. Of course this isn’t looped
:

<?php
$prev = get_permalink(get_adjacent_post(false,'',false));
$next = get_permalink(get_adjacent_post(false,'',true));
?> 

<div id="navarrows"></div>
	<a class="navLink" href="<?php echo $prev; ?>">
		<div class="left column"> <div id="leftcol"> <p>back</p> </div> </div></a>
	<a class="navLink" href="<?php echo $next; ?>">
		<div class="right column"> <div id="rightcol"> <p>next</p> </div> </div></a>