Torre Astura, formerly an island called by the ancients merely Astura (Greek: ), is now a peninsula in the comune of Nettuno, on the coast of Latium, Italy, at the southeast extremity of the Bay of Antium, on the road to Circeii. The name also belongs to a medieval coastal tower in the same site, as well as to the river which rises at the southern foot of the Alban Hills, and has a course of about 33 km before flowing into the sea immediately to the southeast.