Lake Nemi (Italian: Lago di Nemi, Latin: Nemorensis Lacus, also called Diana's Mirror, Latin: Speculum Dianae) is a small circular volcanic lake in the Alban Hills 30 km (19 mi) south of Rome in the Lazio region of Italy. It takes its name from Nemi, the largest town in the area, which overlooks it from a height.
It was formed in an ancient volcanic crater created at least 36,000 years ago.
The Alban Hills (Italian: Colli Albani) are the caldera remains of a quiescent volcanic complex in Italy, located 20 km (12 mi) southeast of Rome and about 24 km (15 mi) north of Anzio. The 950 m (3,120 ft) high Monte Cavo forms a highly visible peak in the centre of the caldera, but the highest point is Maschio delle Faete approximately 2 km (1.2 mi) to the east of Cavo and 6 m (20 ft) taller. There are subsidiary calderas along the rim of the Alban Hills that contain the lakes Albano and Nemi. The hills are composed of peperino (lapis albanus), a variety of tuff that is useful for construction and provides a mineral-rich substrate for nearby vineyards.
Diana Nemorensis ("Diana of Nemi"), also known as "Diana of the Wood", was an Italic form of the goddess who became Hellenised during the fourth century BC and conflated with Artemis. Her sanctuary is on the northern shore of Lake Nemi beneath the rim of the crater and the modern city Nemi.
The worship of Diana at Nemi was supposedly instituted by Orestes, who fled with his sister Iphigenia to Italy, bringing with him the image of the Tauric Diana hidden in a mound of sticks. After his death, the myth has it, Orestes' bones were transported from Aricia to Rome and buried in front of the Temple of Saturn, on the Capitoline slope, beside the Temple of Concord.
Nemi is a town and comune in the Metropolitan City of Rome (central Italy), in the Alban Hills overlooking Lake Nemi, a volcanic crater lake. It is 6 kilometres (4 mi) northwest of Velletri and about 30 kilometres (19 mi) southeast of Rome.
The town's name derives from the Latin nemus, or "holy wood". In antiquity the area had no town, but the grove was the site of one of the most famous of Roman cults and temples: the Temple of Diana Nemorensis.
The Temple of Diana Nemorensis was part of an ancient Italic monumental sanctuary erected around 300 BC and dedicated to the goddess Diana. It was a popular place of worship until the late imperial age.
The temple was situated on the northern shore of Lake Nemi, beneath the rim of the crater and the modern city of Nemi. Large parts of the terraces and buildings remain today.