Monte Circeo or Cape Circeo (Italian: Promontorio del Circeo, Latin: Mons Circeius) is a mountain remaining as a promontory that marks the southwestern limit of the former Pontine Marshes. Here on this beautiful hill over the South Tyrrhenian Sea In 1939, the skull of a Neanderthal man was found in the Guattari Cave by a team led by Alberto Carlo Blanc. Upon the east end of the promontory ridge are the remains of an ancient, a polygonal structure that roughly forms a rectangle and that measures about 200 by 100 meters. The blocks are very carefully cut and jointed; right angles were intentionally avoided. The wall stands almost entirely free, as at Arpinum—polygonal walls in Italy typically form embanking walls—and increases considerably in thickness as it descends.