Richborough, the fort protected a sandy inlet on the Wansum channel that separated the island of Thanet from the rest of Kent. Ptolemy (150) recorded Routoupiai and Lucanus Rutpina litora. The Notitia Dignitatum tells us that this was the headquarters of the Prefect of the Legio II Augusta and uses the form Rutupis. This developed through Bede (Reptacaestir). A British stem rut has been suggested with the meaning 'ditches'.

This is one of the landing places used by the Roman invading army in 43. A fortified bridgehead has been detected. Later, a monumental arch on the site marked the Claudian triumph over the British tribes. These were all swept away by the building of the Saxon shore fort whose walls still stand to 7 metres in places.