Now entirely filled in, Fréjus old port, whose remains have been listed as a Historic Monument since 1886, is an artificial basin, dug out of the marsh land which lined the rocky outcrop on which the town was built. It is therefore located inland, approximately 1,200 m from the sea.
In ancient times, the shore was approximately 900 metres from the port. You can follow the canal which connected the port to the sea for 460m, thanks to a crenellated wall which ran along its west side. The basin is shaped like an irregular polygon, measuring around 17 hectares. It was surrounded with quays and was limited to the south by a 560m long parapet. The entrance of the port featured a construction known as "Augustus' Lantern", which is, in fact, a daymark.
The hexagonal, 10m high construction, with a polygonal roof, lies atop an even older building, made up of two semicircular exedrae. To the north-west side of the basin, archeological excavations have unearthed an esplanade leading to an inner harbour along slipways or inclined surfaces (beneath Porte d’Orée car park). The port, which has remained almost entirely intact since Antiquity, was used during the Middle Ages and right up to the 17th century, when it was known as the "Étang" [Pond] because its surface area had significantly diminished. Fréjus Port, which served battle ships captured by Octavius-Augustus from Cleopatra in 31 B.C during the battle of Actium, is one of the most important maritime sites of the Roman world.