The Crypt of the Original Sin was the cult site of a Benedictine rock monastery of the Lombard period. It is embellished with a cycle of frescoes dated between the 8th and 9th centuries, painted by the artist known as the Painter of the Flowers of Matera and expressing the historical characteristics of Benedictine-Benevento art. The left wall is enlivened by three niches, on which the triarchies of the Apostles, the Virgin Queen and the Archangels are respectively depicted. The back wall, on the other hand, is enlivened by a large pictorial cycle depicting episodes of the Creation and of the Original Sin.