Originally a three-aisled Romanesque basilica dating from ca. 1080. Parts of the crypt and some wall paintings survive from this phase. In 1135 it became the abbey church of an Augustinian monastery (dedicated to St. Leonard of Noblac, died 559). The Basel earthquake of 1356 destroyed the monastery and much of the church, which was rebuilt in Gothic style beginning in 1360. A new building program was started in 1481, creating a Gothic hall church. From 1489 Hans Niesenberger the elder worked in Basle on the Leonhardskirche.