Mine Howe is a prehistoric subterranean man-made chamber dug 20 feet deep inside a large mound. It is located in the Tankerness area of Orkney, about 5 miles (8 km) southeast of Kirkwall, the capital of Orkney. The origin of the howe (from Old Norse word haugr meaning barrow) is not perfectly understood. Experts believe that it was built roughly 2000 years ago during the Iron Age.