aerial photograph of Burgh Castle Roman Fort Norfolk England UK. Gariannonum was one of the Saxon Shore forts built to defend against Saxon raiders. It was originally twinned with Caistor on Sea with the two forts defending both sides of what was then a large estuary. The fort is remarkably well preserved although the seaward facing wall has long since fallen into the estuary. The fort and adjacent Vicus is owned and managed by the Norfolk Archaeological Trust