The famous round passage tomb shown in the photograph is the largest of all the Boyne valley mounds, covering nearly 1.5 acres. It has two tombs placed back to back, one opens east and one west. Knowth's passage tomb was built during the early Neolithic period (ca 3000-2400 BC).
There are up to twenty other tombs at Knowth, and it is also known for its enormous collection of carved stones, which comprise nearly a quarter of all known Western European Neolithic art.
Sources
Knowth.com is a great place to explore Knowth and other megalithic tomb sites like Newgrange.
George Eogan. 1996 Boyne Valley, in Oxford Companion to Archaeology, Brian Fagan, editor, Oxford University Press, New York.


