The Seine River flows from Dijon in the Alps, through Paris, joining the sea at Le Havre on the French coast. Paris lies 277 miles (445 km) from the river mouth and the slow-moving river is navigable up to 348 miles (560 km) inland from Le Havre, to Paris and beyond. This made it a lucrative trading route and Paris a prosperous city even back in the days of the Roman Empire.