Cliff and man-made caves
The southern side of the Cliff, with the many man-made cavities that open onto the valley below, gives us a chance to see what is hidden inside the volcanic mass on which the city stands. Originally these caves did not communicate directly with the outside world but as time passed parts of the vertical tufa and pozzolana walls of the cliff were broken off in landslides and the cavities were partially destroyed, or changed in function.
There are a number of caves on this side of the cliff where the outer wall is missing. They thus face out onto the valley and the three remaining inner walls are riddled with small square niches or cubby-holes, arranged in superposed staggered rows. These were colombaria, or dovecotes, where pigeons were raised for food. While the custom dates back to Roman times, numerous documents mentioning “palummariis” bear witness to the fact that it was particularly common in Orvieto in the Middle Ages. As time passed they fell into disuse and when rediscovered in the nineteenth century were erroneously thought to be Roman funeral colombaria, for burials, with which they really have nothing in common.
Other types of structures which were partially destroyed by landslips can also be identified along the PAAO walk. Remnants of the Etruscan city of Velzna include drainage tunnels and deep shafts with pedarole, or footholds, arranged along the opposing vertical sides to be used in climbing in or out using the contrast method of mountain climbing.
Most of the many entrances at the base of the cliff lead to caves where pozzolana, the basic material for making cement, was quarried. These caves were also used as stables or for storing agricultural instruments, particularly around Cannicella which has always been the vegetable garden for the inhabitants of Orvieto.