Volsinii is situated in a strategic position on the eastern side of Lake Bolsena along the route of the ancient via Cassia. It was founded after the destruction of Volsinii Veteres, Etruscan Velzna seat of the Fanum Voltumnae, by the Romans in 264 B.C. Volsinii was a civita foederata of Rome and probably remained so until the end of the Social War, following which it became a municipium ascribed to the Pomptina tribe.

The remains of the city were mainly excavated by the École Française de Rome. Between 1962 and 1982, the French team excavated the entire central sector, uncovering both the forum with tabernae, the basilica, several roads, a bath complex and two domus denominated the House of the Paintings and the House of the Nymphaeum.

As part of the new project at Volsinii, the first excavations took place in March-May 2019. The research concentrated on the area of the House of the Nymphaeum, where the presence of three different construction phases was particularly important not only for defining the development of the domus itself, but also the town’s diachronic development. The trench (3 × 3 m) was opened in one of the rooms closing the north-western side of the House of the Nymphaeum, delimited by walls presenting three different construction techniques. The evidence suggested that the earliest construction was in opus quadratum, visible at least in the bottom course. Subsequently, an opus Africanum wall was built abutting the opus quadratum wall, which on a NE-SW alignment, occupied all of the central and southern sectors of the area. The latest technique documented in the excavation area was that identified by the French team as opus incertum, present in the central-northern sector. Regarding the chronology of the opus quadratum wall, the preliminary study of the materials recovered from the layer cut by its foundation trench date to the second half of the 3rd century B. C.