The underground caves of Orvieto were excavated over 3,000 years ago by the Etruscans, who were the first to settle on the tuff cliff for security and strategic reasons, and had to find water to survive in this elevated location. Rainwater seeped through the tuff stone until it reached the limestone layer. In the Middle Ages, locals resumed using the wells and created an aqueduct to transport the water. Remains of this water conduit can still be seen throughout the city.

It is a fascinating network spanning several kilometers, with caves containing thousands of shafts, most of which are now inside private homes. Visits are only possible through a guided local tour, which reveals the various uses of the caves over the centuries, up to World War II. The view from the entrance to the site is also highly recommended.