The Cave Church of San Basilio, located in the Piaggio district, has a structure made up of 4 naves and aisles, separated by irregular columns and pilasters. The original apse of San Basilio is situated to the side of the entrance. Modern plasterwork has probably covered over traces of frescoes, while the three 16th century altars at the north end and the 18th century altar at the east end can still be seen. The Rione Piaggio is the oldest district in the city, together with Fondovico, where you can find the church of Santa Lucia and the remains of the apse of the cave church of Santa Maria la Neve.