In the basement of the S.Andrea Church you can see the remains of ancient periods and 4 different evolutionary phases: the most remote the Bronze Age and it is evidence of finds of bronze and ceramic objects of daily use.
The next phase attributable to the Etruscan period, (a particularly flourishing age for all the city, named Velzna) with ruins of ancient road pavements made of local basalt stones.
The third phase of the Roman era witnessed only by few ruins and stratifications that testify to the abandonment of the city itself after the Roman conquest.
The last cultural phase is the complex evolution of the city on the cliff, and it witnesses the birth of a first Christian community in Orvieto. Beautiful mosaic floors reveal the shape of an old Christian church, probably the first church built in the city. The basementof S.Andrea, today, can be visited only with a local guide and only by reservation.
See also other Orvieto underground attractions