Cronk Sumark (Sulby)

Iron Age hillfort in the Sulby valley — IoM's largest valley, which was the main north-south route through the island. Controlling this valley was strategically crucial. The hillfort sits above the Sulby River crossing. WHY DETECT HERE: River crossing points + hillforts = concentrated activity. The ford/bridge area below the hillfort was a choke point on the main route — perfect for finding items dropped by travellers over millennia. Fields between the hillfort and the river are highest priority.