The smaller of the two volcanic lakes in the Castelli Romani, Lago di Nemi was the centre of a cult to the goddess Diana in ancient times, and favourite holiday spot of the emperor Caligula. The Museo delle Navi Romani on the shore was built by Mussolini to house two Roman boats salvaged from the lake in 1932. These dated from Caligula’s time but were tragically destroyed by fire in 1944 – what you see now are scale models.