Today’s Historic Centre stands on the site of the ancient city of Circeii, following its original perimeter. The layout of the ancient city was very simple: a rectangle crossed in the middle by a main road, the decumanus maximus, running north-south.
The decumanus was crossed by secondary streets, the cardines, running east-west. Today’s Corso Vittorio Emanuele runs along the ancient decumanus, while the cardines can be traced in the many little streets that cross it, forming a regular grid.
Apart from the street plan, only limited traces of ancient Circeii survive, with the exception of the mighty Polygonal Walls, well preserved in some stretches, which from the 6th century BC enclosed the ancient town for defence.
The best-preserved stretch of the ancient defences, about three metres thick, can be seen along the south-eastern side of the town, in Via Gino Rossi, where a true layering of buildings is visible: medieval walls were built on the Polygonal Walls, and then modern houses, respecting the ancient line. The walls continue around the whole eastern corner of the town, joining the Ancient Gate, one of the oldest entrances to the fortified town. They do not survive on the north-western side, which suggests there was no defensive wall along that stretch.
The polygonal fortifications of the Historic Centre differ greatly from those of the Acropolis in their building technique. They are built with a more primitive system, known as the “first style”, using irregular limestone blocks, roughly hewn and unpolished, of varying shape and size, laid without mortar and often set in place just as they were quarried from the mountain rock.
The “first style”, unlike the later “second and third styles”, in which the formal developments gradually acquired by the architects of the polygonal technique are evident, is considered the oldest, although it cannot be precisely dated.
However, this technical and formal feature of the polygonal walls of the lower town provides an important clue that Circeii is indeed older than the Acropolis above, dated to the 4th century BC. The archaeological evidence is confirmed by written sources. Three Latin historians mention the colony of Circeii: Livy in his monumental history of Rome “Ab Urbe Condita”, Dionysius of Halicarnassus in “Roman Antiquities” and Diodorus Siculus in his “Bibliotheca Historica”.
Although these works often draw on myth, especially when dealing with the distant origins of Rome in the 8th century BC, both Livy and Dionysius speak of the military colony of Circeii, founded at the end of the 6th century by the Etruscan king Tarquin the Proud to halt the advance of the Volsci south of Anzio.
The colony of Circeii, led by Tarquin’s son Arruns, was founded because the Circeo was a highly strategic place for controlling southern Lazio, almost a natural lookout over the Tyrrhenian Sea: “Praesidia urbi futura terra marique”.
In 393, as Diodorus Siculus reports in his “Bibliotheca Historica”, after a brief period of Volscian rule, the colony of Circeii was refounded and enrolled in the Pomptine tribe, making use of what remained of the military colony of the Tarquins: the Cyclopean walls.
