Nemi

The crater lake of Nemi south of Rome was ringed by the sacred grove and sanctuary of Diana Nemorensis, Diana of the Wood. From the sixth century BC the grove was a common holy place of the Latin cities; the temple was built around 300 BC.

Legend traced the cult to Orestes and Iphigenia, who were said to have brought the image of the Tauric Diana to Italy. A runaway slave who broke a branch from the sacred oak might challenge the priest to mortal combat, and if he killed him became king of the grove.

Each August the festival of the Nemoralia drew pilgrims who garlanded their boats with flowers on the lake. Caligula built two enormous floating pleasure palaces on the lake, later sunk and forgotten.