Originally the area was an undifferentiated part of the south side of the Thames, which was low-lying marshland unsuitable even for agricultural purposes. There is evidence of Roman occupation. As at Lambeth Marsh, the settlement was built on raised through roads over the marsh lands. These were likely summer residences, for in winter the land was under water. A monastery is known to have existed at Bermondsey before 715 AD. Bermondsey is likely to have been a higher, drier spot in an otherwise marshy area.