Atrani arises in the valley bottom created by Dragone river that coming down from mountains which surround Scala, eroded this deep fracture between Aureo Mountain, so called because of the golden colouration produced by sun light on calcareous stone, and Civita Mountain, which overlooks it in the eastern part.

Exactly on these mountain walls and especially on the one of Aureo Mountain there are numerous phenomenon of carsism which originate grottos more or less deep of which the major one, called Masaniello grotto, encloses a lot of labored stone elements formed by very hard water. It is easy to visit because it is not very deep and it represents a nice mix of nature and history since inside it is possible to see traces of human attending.