The Ear of Dionysius, a cave shaped like an ear, in Syracuse, Italy.

The Ear of Dionysius (Orecchio di Dionisio) is a large ear-shaped cave located at the end of the Latomia del Paradiso (Heaven's Quarry). The cave is 23 meters high, and its immense size is evident when you see photos of it with people for scale. The cave was named by the painter Caravaggio. Dionysius was the name of the tyrant who once ruled Syracuse. Voices inside the cave echo all the way to the outside, which is quite surprising. Even a small voice carries well. According to legend, the tyrant Dionysius used to imprison enemy captives in this cave to eavesdrop on their plots and secret conversations.