Researchers have excavated King Arthur's Hall, a rectangular enclosure in southwest England, and determined that it dates to at least 3000 B.C.E.

In the Cornish moorlands of southwest England lies a mysterious mound of stone and turf. Now covered with grass, the site was previously thought to be a medieval livestock pen built around 1000 C.E. Now, researchers have concluded the construction is actually 4,000 years older—dating to at least 3000 B.C.E., during the Neolithic period.

Known as King Arthur’s Hall, the unique site is located in Bodmin Moor in Cornwall. It’s about 160 feet long and 70 feet wide, and its walls are made of 56 earth-covered stones, which once stood upright. Now, they are all leaning, lying flat or buried.

“There isn’t another one of these anywhere,”