In Upper Midwest: Minnesota on the Wisconsin side
<a href="http://tunnelcity.com/" rel="nofollow">http://tunnelcity.com/</a>
<a href="https://www.facebook.com/pages/category/Just-for-fun/Sandland-181721285219560/" rel="nofollow">https://www.facebook.com/pages/category/Just-for-fun/Sandlan...</a>
This place looks like a hidden social treasure in the making. Lots of engineering and hacking going on here. One of these days I am going to bring my lidars up to Sandland to get point clouds.