One of the largest Neolithic burial grounds on the River Boyne in County Meath, Ireland. It is a circular burial mound containing two passage graves entered from opposite sides. The first is a large but simple passage grave, with several decorated stones but no evidence of corbelling. The second tomb, also a passage grave, has a corbel-vaulted burial chamber with three niches. One of these contained a stone basin ornamented with grooves and circular designs, and there is further carving on the walls of the tomb itself. The central mound was surrounded by at least 15 smaller tombs, each under its own cairn, and these 'satellite' tombs included both entrance graves and passage graves of cruciform plan. Knowth is one of the three principal elements of the Boyne Valley megalithic cemetery, dating from the 4th millennium BC. Knowth was later reoccupied in the early historic period when Souterrains were constructed within the mound. Excavations have also revealed the remains of the Early Christian royal center here, belonging to the Northern Brega known from the Irish annals.