About twenty years later, after a period of abandonment, a new smaller Roman auxiliary fort was constructed and was possibly occupied, along with a civilian vicus, until the reign of the Emperor Hadrian.

From the late 2nd to the mid-3rd century, civilian timber buildings associated with iron working occupied the site.

Around 290, a 9-acre (3.57 hectare) shore fort was built on the site, not unlike the almost complete example at Portchester in Hampshire.

Its walls were ten feet thick and it was positioned to control access to the upper reaches of the River Severn.

The ruinous fort appears as the residence of 'King Ynwyl' in the story of Geraint and Enid, a medieval romance associated with the Mabinogion.