This 2nd century Roman fort was once a large center of fortification near Hadrian’s Wall, but now the isolated site has been abandoned since the 4th century, the secrets beneath its earthern walls only excavated by the moles that live in its grounds.

It’s speculated that the fort was built as a defense for the nearby silver and lead mines, and although it is now part of a private farm, there are efforts to turn it into a tourist destination. As a designated Scheduled Ancient Monument, it is unable to be excavated, but the laws of humans don’t extend to moles. These moles, which each can dig around 60 feet of tunnels a day, push shards of pottery, beads, and other artifacts to the surface, which are collected by volunteers in an annual molehill survey.