Here is an article (in English) from the official website of the Lazio region of Italy, which is thre region that contains the city of Rome. This article is about the city of Bagnoregio:

One of the most beautiful old towns in Italy, it is also disappearing. Civita di Bagnoregio, a quarter of the Municipality of Bagnoregio, is located on a tufa rock hill and can be reached only by crossing a pedestrian bridge.

Called the “dying city” by Bonaventura Tecchi, who was born here, Civita di Bagnoregio risks disappearing because the tufa hill where it is located is being eroded at the base by the continuous action of the two streams in the valleys below as well as by the effect of rain and wind.

Read all about it here -> Civita di Bagnoregio, the dying city