Mount Circeo is the limestone headland that closes the southern end of the long Sabaudia beach. Seen from a distance it looks like a recumbent figure — early travellers thought they could make out a sleeping witch — and the stark white cliffs falling into the sea are unmistakable. Several walking trails leave from the village of San Felice Circeo on the inland side and climb to the summit (541 m). The harder routes scramble through limestone outcrops and Mediterranean scrub; an easier track follows the northern slope through forest.
The summit gives panoramic views over the whole Pontine plain, Lake Sabaudia, and on clear days the Pontine Islands out at sea. There are several caves on the flanks of the mountain — including the Grotta Guattari, where a Neanderthal skull was found in 1939 — which can be visited with a guide.