Portus Lemanis is one of four Roman Forts built in Kent, the others being Dover, Reculver & Richborough. Portus Lemanis dates from AD260 and was used until around AD370 when it was adandoned.
Unfortunetely the footpath that runs down from Lympne to West Hythe is no longer opened to the public because the land is now private. This was one of the two paths that I would use to walk home from school, now that's not possible, very sad!