The Crypt of the Redeemer (or of the Madonna della Grotta) is an underground rock church. It was originally an ancient Roman chamber tomb from the Imperial Age located in Via Terni, connected to an ancient spring water well. The cave has a circular shape with a diameter of about eight metres, and the walls are decorated with frescoes of great artistic value dating back to the early 12th century. The crypt was part of the Church of Santa Maria di Murivetere, which was closed to worship in 1578. Tradition has it that the first Christian worship according to the Byzantine liturgy was celebrated in the crypt. In the 12th century, it was adorned with frescoes of remarkable beauty, including 'Christ Pantocrator between St John and the Virgin in the apse', while saints such as St Basil, St Euplo and St Blaise appeared on the side walls.