Dubris, also known as Portus Dubris and Dubrae, was a port in Roman Britain on the site of present-day Dover, Kent, England. As the closest point to continental Europe and the site of the estuary of the Dour, the site chosen for Dover was ideal for a cross-channel port. The Dour is now covered over for much of its course through the town. In the Roman era, it grew into an important military, mercantile and cross-channel harbour and – with Rutupiae (Richborough Roman fort) – one of the two starting points of the road later known as Watling Street. It was fortified and garrisoned initially by the Classis Britannica, and later by troops based in a Saxon Shore Fort. Julius Caesar At the start of his first attempt to conquer Britain in 55 BC Julius Caesar initially tried to land at Dubris, whose natural harbour had presumably been identified by Volusenus as a suitable landing place. However, when he came in sight of shore, the massed forces of the Britons gathered on the overlooking hills and White Cliffs of Dover dissuaded him from landing there, since the cliffs were "so close to the shore that javelins could be thrown down from" them onto anyone landing there. After waiting there at anchor "until the ninth hour" (about 3pm) waiting for his supply ships from the second port to come up and meanwhile convening a council of war, he ordered his subordinates to act on their own initiative and then sailed the fleet about seven miles along the coast to an open beach. Classis Britannica fort The Roman fleet in British waters, the Roman navy's main purpose was protecting the Gaul-to-Britain routes and supporting the land army in Britannia, not defending Britain from invasion. For this reason, its main harbor was in Gesoriacum (Boulogne), not Dover. However, it did have other, smaller bases in Britannia itself, at Rutupiae and Dubris. Lighthouses Two lighthouses, each called the "Pharos", were built at Dover soon after the Roman conquest. Proposals of their date range from 50 (seven years after the invasion of 43), 80 or (since the building includes tiles identical to the mansio in the town built at that date) c. 138, though the general consensus is for a 1st-century AD date. They were sited on the two heights (Eastern Heights and Western Heights) and modelled on the Tour d'Ordre built for Caligula's aborted