Trethevy Quoit (Cornish: Koyt Tredhewi)[1] is a well-preserved megalithic structure between St Cleer and Darite in Cornwall, United Kingdom. It is known locally as “the giant’s house”.[2] Standing 9 feet (2.7 m) high, it consists of five standing stones capped by a large slab and was added to the Heritage At Risk register in 2017. Like other portal structures of this type, Trethevy Quoit was originally covered by a mound. The remnants of this suggest a diameter of 6.5 metres (21 ft). The remaining seven stones and the 3.7-metre (12 ft) long and 10.5-ton cover slab were inside the mound. At the upper end of the cover slab is a natural hole, which may have been used for astronomical observation. The group of horizontal stones is composed of a fallen back wall, two overlapping side wall stones, a front stone and a somewhat remote flanking stone. Source: Wikipedia.org