Cawfields Milecastle 42, near Haltwhistle, Northumberland
- Built as part of Hadrian’s Wall in AD 120s.
- Site of a quarry of the hard black rock called dolerite, or whinstone by the locals, that closed in 1944.
- Milecastle outline sitting on the slope of the Whin Sill.
- Long wall sections that snake off to the east.
- Excellent view of the deep-rutted vallum, the defensive ditch that runs south of the wall.
- All that remains of the quarry is the lake and the scarred Whin Sill.