At the Montélimar hospital ( Drôme, Auvergne- Rhône-Alpes, France ) on the upper floors, window sills serve as nesting boxes for pigeons.
( Photo taken through a window )
<a href="//commons.wikimedia.org/wiki/User:Celeda" title="User:Celeda">Celeda</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>