Orvieto - The Well of St. Patrick

One of the main attractions in Orvieto is the Pozzo di San Patrizio, or the Well of St. Patrick. This well was dug deep enough to ensure a water supply to the city if it came under siege. The unique thing is that the fairly wide passageway down to the water is constructed as a double-helix, meaning that the donkeys going down to the bottom could continue on up without having to turn around and pass the ones coming down. There are windows in the interior of the well all the way to the bottom (175 feet deep, 45 feet wide). 

Here are a few photos.

Across to the other side:

from the bottom looking up

Looking down from the top: