Tinkinswood burial chamber was constructed around 6000 years ago about 1000 years before Stonehenge.
The structure would have originally been covered with earth.
The original excavation took place at the Tinkinswood burial chamber in 1914 by John Ward who at that time was the Keeper of Archaeology at the National Museum of Wales.
When the chamber was excavated a brick pillar was inserted to support the roof, and the distinctive herringbone stonework of the forecourt was added to the original supporting walls. There were 920 human bones found from at least 50 people buried during the Neolithic period.
The limestone capstone at Tinkinswood weighs approximately 40 tons and measures 24 feet (7.3 m) x 14 ft (4.3 m), it is thought to be the largest in Britain, and also in Europe.
As always local myths are associated with the structure.
The best known of these tales say that anyone spending the night here on the eve of May Day, Midwinter, or St John's Day (23 May) will either go mad or become a poet.