Richborough Castle Richborough Castle contains the ruined remains of a Roman Saxon Shore Fort . It situated in Richborough near Sandwich , Kent . The site has many phases of Roman remains , collectively known as Richborough Fort or Richborough Roman Fort , still visible today and under the care of English Heritage . " Rutupiæ " ( its Latin name ) was founded by Romans when they landed in England in AD 43 . It was a major port of Roman Britain ( with Dubris , it was one of the start - points for the Roman road of Watling Street , which ran on to Canterbury and London ) . Earth fortifications were first dug on the site in the 1st century , probably was as a storage depot and bridgehead for the Roman army . This transformed into a civilian and commercial town , which was later replaced by a Saxon Shore Fort around the year 277 . The later fort is believed to have been constructed by Carausius . History . Invasion of 43 A . D . . It has commonly been accepted that Richborough was the landing site for the 43 AD invasion . This is because of the existence of mid - 1st century AD ditches and fortifications on the site . These ditches and fortifications are assumed to have been built to protect their bridgehead and supply depot . However , the site of the Claudian invasion of Britain in the year 43 AD is not stated in the surviving written sources and has recently started to be debated . Civilian town . As the fighting moved north , Rutupiae became an increasingly large civilian settlement . There were temples , an amphitheatre ( visible as a hummock in the grass 5 minutes walk from the main site ) , and a Mansio ( first built in 100 , it was a building that went through several phases , being a hotel for visiting officials , bath house and administration building ) . As a port , the town always competed with Portus Dubris ( modern Dover ) , about 15 miles ( 25 km ) south along the coast . However , Richborough was widely regarded throughout the Roman Empire for the quality of its oysters ( they are mentioned as on a par with those from the Italian Lucrine Lake in Juvenal , " Satires " 4 . 141 ) , whilst " Rutupine shore " was used as a synonym for the whole coast of Britain in some literary works . Triumphal arch . A major quadrifrons triumphal arch was erected straddling Watling Street , the main road from Richborough to London . Its position and size suggest it may have been built to celebrate the final conquest of Britain after Agricola ’ s victory at Mons Graupius . Almost 25 metres high , it had a facade of high quality , Italian granite . Standing as it did between the port and the province , passage through the arch signified formal entry into " Britannia " ( cf the similarly maritime arch at Ancona ) . Only its foundations and mound are still visible . Saxon Shore Fort . During the late 3rd century this ( by now large ) civilian town was remilitarized by its conversion into a Saxon Shore Fort . The Saxon Shore Forts were a series of forts built by the Romans along the Channel on the English and French sides to guard against invading Saxon pirates . Construction of the fort here is believed to have started in 277 and completed in 285 . This involved the demolition and reuse as spolia of the triumphal arch , and numismatic evidence suggests it occurred during the reign of Carausius . The fort was in area and was surrounded by massive walls , forming an almost perfect square . However , the north and south walls were constructed differently . The north wall was built by separate gangs of laborers , while the south wall seems to have been built as a single unit . This suggests that the north wall of the fort was built sometime after the construction of the south wall . In some places , the walls reached over 25 feet ( 8 m ) in height , and were built of small ashlar and double - tile courses . The main entrance of the fort was in the west wall . The walls stand to a great height and were of such high quality that they only recently needed repointing . Though some stone buildings existed in the interior of the fort , most of its buildings seem to have been composed of timber . There existed a central rectangular building built of stone , which was probably the principia ( headquarters ) . Small , stone - built baths were also present at Richborough . Church at Richborough . There exists an unexplained structure at Richborough that is believed to be a font . Today , this structure is almost entirely destroyed . The hexagonal font discovered during the excavations at Richborough suggests that baptisms could have been a function of this church . The church was probably built at the end of the 4th century or at the beginning of the 5th century . It seems plausible that the church was built of wood . Roman withdrawal . During the decline of the Roman Empire , Richborough was eventually abandoned by the Romans and after this , the site was occupied by a Saxon religious settlement . Excavations . Recent Excavations carried out in late 2008 of an 90 metre section of Roman wall uncovered the original Roman Coastline along with the remains of a Medieval Dock . The discovery and excavation of the beach itself has pinpointed its geographical relationship to the site ' s earthworks , proving that the earthworks were a beachhead defence , protecting around 700 metres of coast . The site is now two and half miles inland from the current coastline .