Milefortlet 21 and the Saltpans of Crosscanonby

Milefortlet 21 is now the only element of Hadrian's coastal defences of the northwest frontier (and thus of the Roman Empire) to have been wholly excavated. The site consists of a viewing platform over the exposed excavation, and is part of the wider Frontiers of the Roman Empire UNESCO World Heritage Site.

For nearly 700 years, salt was made from sea water along the Cumbrian coast. Crosscanonby Salt Pans, next to Milefortlet 21, are the remains of one of the new generation of salt works, built around 1650 by the Senhouses of Netherhall. The works appear to have closed 86 years later. Until 1970, the salters' cottages and stables still remained at the site.