Banna, now known as Birdoswald Roman Fort, was a fort, towards the western end of Hadrian's Wall, in the Roman province of Britannia. Today the site is occupied by a former farm called Birdoswald. As of 2005, it is the only site on Hadrian's Wall at which significant occupation in the post-Roman period has been proven, and it is subject to a long-term archaeological programme under the directorship of Tony Wilmott.
It is one of the best preserved of the 16 forts along Hadrian's Wall. The fort is situated in a commanding position on a triangular spur of land bounded by cliffs to the south and east overlooking a broad meander of the River Irthing in Cumbria. In Roman times, the fort was known as Banna, reflecting the geography of the site.
Cumbria County Council were responsible for the management of Birdoswald fort from 1984 until the end of 2004, when English Heritage assumed responsibility.