Knowth passage tomb is a major archaeological complex that was at the centre of burial and ceremonial activities from the Neolithic to the medieval period. The main mound consists of two passage tombs placed back to back, one entrance to the east, the other to the west. The mound is decorated with 127 kerbstones and is surrounded by eighteen satellite tombs. The two main tombs consist of long passages that open into chambers roofed with large capstones. The chamber in the eastern tomb contains three recesses with their stone basins to hold the remains of the dead. Grave goods discovered when the tomb was excavated included beads, pendants and a finely decorated flint macehead.
Large-scale excavations at the Knowth complex conducted by Professor George Eogan for over forty years uncovered intermittent burial on the site through the Bronze Age and the late Iron Age. Knowth was the centre of an early medieval kingship and was converted into a highly defended residence from the 7th to the 10th century, with a settlement built on the top of the mound during that period. As with Newgrange, Knowth was regarded as a síd, an entrance to the otherworld although this did not prevent the Vikings from attacking it in AD861.