There is a town pretty much underground in Australia. http://www.google.com.au/images?oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&q=coober+pedy&um=1&ie=UTF-8&source=univ&ei=A4tTTNiqFpDQcarOkMAM&sa=X&oi=image_result_group&ct=title&resnum=5&ved=0CEIQsAQwBA&biw=1809&bih=942
Cool but...