Ventilation shaft of the <i>Tongrube Barbara</i>, Hirschau-Ehenfeld, district Amberg-Sulzbach, Bavaria, Germany
<a href="//commons.wikimedia.org/wiki/User:DKrieger" title="User:DKrieger">DKrieger</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>