 Complete the following phrase:  The Saxon Shore forts were built by the Romans in the 3rd century AD as a defence against overseas raiders. In Norfolk the ruins of the forts built at Burgh Castle Roman Gariannonum, guarding the estuary across from the island of Flegg, still exist, but there is now little remaining of the forts at Brancaster Branodunum built on the north coast, and at Caister-on-Sea, on the east coast and near Burgh Castle. After the last of 