Clonmacnoise (Irish: Cluain Mhic Nois, “meadow of the sons of Nos”) is a monastic site overlooking the River Shannon in County Offaly. The extensive ruins include a cathedral, castle, round tower, numerous churches, two important high crosses, and a large collection of early Christian grave slabs (the last two on display in the excellent site museum).
Clonmacnoise was founded in 548 by St. Ciaran, the son of a master craftsman. The settlement soon became a major center of religion, learning, trade, craftsmanship and politics, thanks in large part to its position at the major crossroads of the River Shannon (flowing north-south) and the gravel ridges of the glacial eskers (running east-west).
The settlement was also situated between the two provinces of Meath and Connacht, and benefited from the patronage of powerful provincial kings. Clonmacnoise was originally associated with Connacht, but from the 9th to 11th centuries allied itself with Meath. In the late 11th and 12th centuries, allegiance reverted once again to Connacht. The last high king of Ireland, Rory O’Connor, was buried in Clonmacnoise’s cathedral in 1198.
Religion was the central focus at Clonmacnoise, but it always had a large lay population and thus looked more like a town than a monastery. The houses and domestic buildings were made of wood and have not survived, but there is a reconstruction of one such building in the site’s museum. The earliest churches at Clonmacnoise were also made of wood, but from the 10th century onward they were built of stone.
Like nearly all monastic settlements in Ireland, Clonmacnoise was plundered on several occasions by invaders, including the Vikings and Anglo-Normans. It then fell into decline from the 13th century onwards until it was destroyed in 1552 by the English garrison from nearby Athlone.
Clonmacnoise was designated a national monument in 1877 and is now overseen by the Office of Public Works (OPW).