Ravenglass was an important naval base for the Romans in the 2nd century, GLANNAVENTA. Little remains now of their large fort except for the remarkable bath house, now known as Walls Castle. This is one of the largest surviving Roman structures in England, about 40 feet by 90 feet with walls over 12 feet high (4 meters), and containing everything from hot saunas to cold baths.

Ravenglass was a regional supply point for much of the north west, with a Roman road from Ravenglass through the Hard Knott Pass to the Roman fort at Ambleside. Ravenglass was occupied by the Romans for over 300 years, and had a garrison of a thousand soldiers.

The property is in the care of English Heritage.