The coast between Gaeta and the Circeo headland offers some of the most varied day-trip territory in central Italy. All of the destinations below are within 40 km and reachable by car or public transport.
Sperlonga (15 km south) is the most obvious excursion: a whitewashed hilltop village above a superb beach, with a national archaeological museum built around the Grotto of Tiberius — a sea cave that served as the emperor's dining room, decorated with enormous sculptural groups depicting scenes from the Odyssey. The sculptures, discovered in 1957, are some of the most dramatic Hellenistic-Roman works in existence.
Formia (8 km north), the nearest town and transport hub, is worth a look beyond its function as a rail stop. It contains the tomb traditionally identified as that of Cicero, who owned a villa nearby (at Formiae) and was murdered on the Via Appia just outside town in 43 BC.
Monte Circeo (40 km north) is a limestone headland that juts dramatically into the sea, forming the southern tip of the Pontine coast and a national park. The summit has Neolithic walls and extraordinary views. The town of San Felice Circeo below is a pleasant base. The headland is associated with Circe of Greek mythology — the Homeric enchantress was said to live here.
Terracina (35 km north) has a Roman forum still standing at mid-town level, with the dramatic Temple of Jupiter Anxur visible on the clifftop above. The old town is compact and genuinely old; the modern beach resort below is interchangeable with others on the coast.