The Salzburg catacombs were carved into the rock of the Mönchsberg. The Gertraudenkapelle was consecrated to Thomas Becket in 1178. Later the chapel was also consecrated to Gertraud von Nivelles.
The arched niches were created in 1865.
<a href="//commons.wikimedia.org/wiki/User:Isiwal" title="User:Isiwal">Isiwal</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>