The Church of Saint-Pierre-aux-Nonnains, with origins dating back to the fourth century AD, is the oldest church in all of France and one of the oldest monuments in the city. It is a wonderful example of a pre-medieval cathedral. It was a gym and spa for the Romans and then turned into a church in the seventh century. Its nave was built in the eleventh century, and it is surrounded by a very spacious garden. Today, it is considered a cultural center for concerts and exhibitions, and an architectural witness to two thousand years of history.