Portus Lemanis, also known as Lemanae, was the Latin name of a Roman Saxon Shore fort, settlement and port in southern Kent.

[1] However, there is archaeological evidence of much earlier use as a naval base: tiles stamped CL BR have been found indicating that sailors or marines of the fleet, the Classis Britannica, were involved in its construction, as well as an inscription dated to the first third of the 2nd century (RIB 66) on an altar stone, dedicated to the god Neptune by a Lucius Aufidius Pantera, prefect of the Classis Britannica.

[2] According to the 5th-century Notitia Dignitatum, the fort was garrisoned by a regiment raised in Tournai (numerus Turnacensium) and formed part of a defence system known as the Saxon Shore under the command of a Count.

[3] The last mention of Lemanis in Latin sources is in the late 7th-century Ravenna Cosmography, by which time the site, along with the rest of Britain, had long been severed from the Roman Empire.

The wall is built of recycled material from earlier structures and bonded with bands of brick, which include several roofing tiles.