Forum Iulii, Ancient Roman settlement in Fréjus, France

Forum Iulii is an archaeological site with Roman-era remains spread across several excavation areas in Fréjus. The discoveries include a forum, an amphitheater, an aqueduct, and structures from private dwellings.

The site was founded in 49 BC as a naval base after a nearby port city opposed the founder. This strategic establishment allowed control of sea routes between Italy and Spain.

The name Forum Iulii means "forum of Julius", after Julius Caesar, who chose the site as Rome's main port in the region after the siege of Marseille in 49 BC. Under Augustus the colony was called Forum Iulii Octavanorum, and it housed veterans of the VIIIth legion. Cnaeus Julius Agricola, conqueror of Britain and father-in-law of the historian Tacitus, was born here in AD 40.

The Roman port has silted up: the coastline advanced about 1,300 m, so the harbour basin and the quay now called chemin de la lanterne d'Auguste lie inland. That quay was 4 m wide and some 560 m long, ending at the 10 m Lanterne tower, a navigational marker rather than a lighthouse. The amphitheatre, 113 m by 85 m, stood outside the west of the ancient city.

The Roman naval base lay on the coast, but the shoreline has advanced about 1,300 m, so the harbour basin now sits inland. The quay known as the chemin de la lanterne d'Auguste ran some 560 m and was 4 m wide; at its end stands the 10 m "lanterne", a tower topped by a pyramid that served as a seamark rather than a lighthouse.