It's not uncommon in some of the older towns and cities in France for newer buildings to be constructed over some of the old streets and a passageway is left through the building for access. Here's an example from my walk this afternoon round the old quarter of the Breton town of Ploërmel.
Another one that rewards viewing on black!
This image is SOOC and is part of my ongoing OCOLOY project - you can read more about it in my profile.
Kev @snaggy