The Roman aqueduct of Fréjus is one of the clearest reminders that this quiet Riviera town was once Forum Julii, an important Roman port and military colony. Its surviving arches and masonry fragments mark the route of a long water supply system that brought fresh water from the hills into the ancient city.
You don't come here for a polished museum experience. The pleasure is in seeing Roman engineering stitched into the modern townscape, with ruined sections appearing near roads, gardens, and residential streets. Pair it with the amphitheatre, the cathedral precinct, and the archaeological museum for a good half-day of Roman Fréjus.