the Catacomb of Santa Caterina d'Alessandria, Chiusi Scalo (Siena), Italy. Entrance.
<a href="//commons.wikimedia.org/wiki/User:Cyberuly" title="User:Cyberuly">Cyberuly</a>
CC BY 3.0
<span class="int-own-work" lang="en">Own work</span> (my Nikon and my Macintosh)