Once on an tidal inlet, the fort is now high and dry and extensively ruined. Its name becomes Bramcestria in Old English. The British form could be bran 'crow or raven' dunon 'fort'. It's design closely resembles that of Reculver. If they are contemporary these two would have been the earliest elements of the Saxon shore fort-line built specifically to extend the reach of the Roman fleet. The fort was dug in the 19th century to reveal a simple trace of curtain wall measuring approximately 170 metres by 170 metres. There was one internal corner tower and towers on either side of the gate. There were no bastions as found on other, later,forts of the Saxon Shore.

The Notitia Dignitatum (first quarter of the fifth century) locates the Commander of the Dalmatian cavalry at Branodunum. This implies that offensive action against landings was the order of engagement and not the passive defence of the fort.

A tile stamped COH I AQV indicates that the first cohort of Aquitanians was at some point stationed here.

Branodunun may have had a sister fort on the opposite side of the Wash. The fort reported in the 17th century at Skegness may have had this rôle but all the forts listed in the Notitia Dignitatum are accounted for.