Carn Euny is an archaeological site near Sancreed, on the Penwith peninsula in Cornwall, United Kingdom. It consists of evidence of both Iron Age and post-Iron Age settlement, with excavation on the site showning activity at Carn Euny as early as the Neolithic period. The first timber huts there were built about 500 BC, and 400-500 years later were replaced by stone huts; the remains of which are still visible.
Carn Euny is best known for the well-preserved state of the large fogou, an underground passageway, which is more than 65 feet long. This fogou runs just below the surface of the ground and is roofed with massive stone slabs.
Wikipedia https://en.wikipedia.org/wiki/Carn_Euny
Address (Unnamed Road), TR20 8RB, United Kingdom
Coordinates 50°6'9.741" N -5°38'1.69" E