CIRCEII, a town of ancient Italy, in Latium, at the foot of Mons Circeius, or Capo Circello, a short distance from the sea, and 10 or 12 miles along the coast from Terracina. It was originally colonized by the Romans in the reign of Tarquin the Proud, who deemed the position favourable for commerce and for repressing the inroads of the Volsci. From its foundation till the date of the Latin War, 340 b.c., it seems at one time to have been subject to the Romans, at another to have espoused the cause of the Volsci, and sometimes to have been independent of both powers. After the Latin War it was recolonized by the Romans; but it continued gradually to decline till the emperors Tiberius and Domitian, attracted to it by the pleasantness of its situation and the excellence of its oysters, erected villas in the neighbourhood. Its ruins are still distinctly visible on the Monte della Cittadella, and consist of walls and gateways built of polygonal blocks.