Around the year 1000, the reputation of Mont-Saint-Michel continued to grow. The first Benedictine monks built a chapel on the site of the primitive sanctuary to welcome pilgrims. The church of Notre-Dame-Sous-Terre is today the oldest part of the Mont and the most moving in its simplicity. During the construction of the Romanesque abbey church, from 1023 onwards, this chapel was reinforced to support the last bays of the nave and the facade, and then gradually sunk into the bowels of the monastery.