Digne-les-Bains - Notre Dame du Bourg

The cathedral was the center of an early diocese (4th century). The building was constructed from 1220/1225 on, using foundations of older structures. When the facade was built the ideas of gothic style had arrived and so a rose window was possible, creating that round light spot in the middle of the nave. During the recent renovation a necropolis has been excavated just under the floor of the nave. The cathedral was always outside the little town, so it was difficult to defend it. In the Wars of Religion it was raided and looted a couple of times from Huguenots as well as from the Catholic League. It was even tried to blow it up. Finally the cathedral was abandoned - and the bishop moved his seat permanently into walled Digne.

Here is more information (in french):
catho04.cef.fr/decouvrir/paroisses/digne/digne2.htm