Part of the town is built on the edge of a deep drop, a ravine characterised by a large area of cave dwellings linked with the dense system of underground dwellings in the “Piaggio” and “Fondovico” districts. While the town’s surviving caves have been changed over the centuries to meet the needs of different uses, for instance as cellars or stables, the vast system of caves all along the nearby ravine still preserves important testimony of the complexity of the cave-dwelling civilisation: numerous cave dwellings are built on different levels, overlapping and linked together by outdoor stairways, with dozens of frescoed churches, roads, tombs, walls and gardens.
The cave church of San Michele is particularly interesting, divided into five naves by rows of columns. The 11th century Padre Eterno church has a single nave and an apse decorated with frescoes, while Santa Maria degli Angeli is divided into three by four large columns and a Christ Pantocrator in the central apse. Sant'Elia is another interesting church, while the Cave of the Seven Chambers incorporates seven interconnected areas dating back to the Neolithic.