Knowth (/ˈnaʊθ/; Irish: Cnoghbha) is a Neolithic passage grave and an ancient monument of Brú na Bóinne in the valley of the River Boyne in Ireland. Knowth is the largest passage graves of the Brú na Bóinne complex. The site consists of a large mound (known as Site 1) and 17 smaller satellite tombs. The mound is about 12 metres (40 ft) high and 67 metres (220 ft) in diameter, covering roughly a hectare. It contains two passages placed along an east-west line.