Mount Circeo

Monte Circeo or Cape Circeo is a mountain remaining as a promontory that marks the southwestern limit of the former Pontine Marshes. Although a headland, it was not formed by coastal erosion – as headlands are usually formed – but is a remnant of the orogenic processes that created the Apennines. The entire coast of Lazio, on which the mountain and the marsh are located, was a chain of barrier islands that was formed on a horst and made part of the mainland by sedimentation of the intervening graben.

Monte Circeo, as it is sometimes also called in Italian, is located on the southwest coast of Italy, about 100 kilometres south-southeast of Rome, near San Felice Circeo, on the coast between Anzio and Terracina. At the northern end of the Gulf of Gaeta, it is about 5 kilometres long by 1.5 kilometres wide at the base, running from east to west and surrounded by the sea on all sides except the north.