It is the oldest known ark to have been used to preserve the ashes of St. John the Baptist. The shape is that of a rectangular building with a sloped “roof” covering  which extends beyond the “walls”, the work is decorated with plant motifs. The panels which compose it tell the life of the Christ’s precursor.

On the front face are the scenes of the artyrdom: Herodias instigates Salome, Herod attends the dance of Salome, the servant carries the head of the Baptist, the executioner is about to perform the Beheading. The front side and the two short sides are decorated with precious  stones, rectangular and oval shaped, cut cabochon. According to a later tradition - the seventeenth-century ark was reported to be a devotional offering from the Emperor Federico Barbarossa.