The monastery of Clonmacnoise (Cluain Mhic Nóis in Irish, meaning "Meadow of the Sons of Nós", is situated in County Offaly, Ireland on the River Shannon south of Athlone.

Clonmacnoise was founded in 544 by St. Ciarán, a young man from Rathcroghan, County Roscommon. (Not to be confused or conflated with St. Ciarán of Saigir, patron of Osraige). Until the 9th century it had close associations with the kings of Connacht. Saint Ciarán choose to found the monastery in the ancient territory of Ui Maine at a point where the major East-West land route(Slighe Mhor) meets the River Shannon after crossing the bogs of Central Ireland known as the Esker Riada. The strategic location of the monastery helped it become a major centre of religion, learning, craftsmanship, and trade by the 9th century and together with Clonard it was the most famous in Ireland, visited by scholars from all over Europe. From the ninth until the eleventh century it was allied with the kings of Meath. Many of the high kings of Tara (ardrí) and Connacht were buried here.

The preserved ruin is managed by the Office of Public Works. An Interpretive Centre is open to the public, the graveyard is in use and religious services are held in a modern chapel.

History

Shortly after his arrival with seven companions – at the point where the major east–west land route through the bogs of central Ireland along the Eiscir Riada, an esker left by the receding glaciers of the last ice age crossed the River Shannon – Saint Ciarán met Diarmait Uí Cerbaill who helped him build the first church at the site. This was a small wooden structure and the first of many small churches to be clustered on the site. Diarmuid was to be the first Christian crowned High King of Ireland. In September 549, not yet thirty-three years of age, Ciarán died of a plague, and was reportedly buried under the original wooden church, now the site of the 9th-century stone oratory, Temple Ciarán.

 

Clonmacnoise Castle

According to Adomnan of Iona, who referenced the testimony of earlier abbots of Iona who had known Columba, St Columba visited the monastery at Clonmacnoise during the time when he was founding the monastery at Durrow. While he was there he prophesied about the future debates in the churches of Ireland about the dating of Easter and claimed that angels had visited the monastery at Clonmacnoise. While he was there, there was a young monk named Ernéne mac Craséni (who would later be famous in Ireland) who tried to touch Columba's clothes while Columba was not looking, but the saint immediately noticed and grabbed the boy by the neck, and then told him to open his mouth and he blessed him, saying that he would teach the doctrine of salvation. 

Towards the close of the seventh century a plague carried off a large number of its students and professors. Clonmacnoise's period of greatest growth came between the 8th and 12th centuries. It was attacked frequently during these four centuries, mostly the Irish (at least 27 times), the Vikings (at least 7 times) and Normans (at least 6 times). The early wooden buildings began to be replaced by more durable stone structures in the 9th century, and the original population of fewer than ten men grew to perhaps 1,500 to 2,000 by the 11th century. Although the site was based around a core of churches, crosses, graves and ecclesiastical dwellings and workshops, it would have been surrounded by the houses and streets of a larger secular community, the metalworkers, craftsmen and farmers who supported the monastic clergy and their students. Artisans associated with the site created some of the most beautiful and enduring artworks in metal and stone ever seen in Ireland, with the Clonmacnoise Crozier (on display in the National Museum of Ireland) and the Cross of the Scriptures representing the apex of their efforts. The Book of the Dun Cow a vellum manuscript dating to the 12th century, was written here and its main compiler, Máel Muire mac Céilechair meic Cuinn na mBocht reputedly murdered in a Viking raid in 1106.

By the 12th century Clonmacnoise began to decline. The reasons were varied, but without doubt the most debilitating factor was the growth of the town of Athlone to the north of the site from the late-12th century. Athlone became the main trading town for the midlands of Ireland, the most popular route for crossing the Shannon, as well as the best-defended settlement in the region. People migrated north from Clonmacnoise to Athlone, and with the fall in population went much of the support that the site needed to survive, and former allies began to recognise the decline in the site's influence. The influx of continental religious orders such as the Franciscans, Augustinians, Benedictines, Cluniacs, etc. around the same time fed into this decline as numerous competing sites began to crop up. Ireland's move from a monastic framework to a diocesan one in the twelfth century similarly diminished the site's religious standing, as it was designated the seat of a small and impoverished diocese.

 

Clonmacnoise at sunset

In 1552 the English garrison at Athlone destroyed and looted Clonmacnoise for the final time, leaving it in ruins.

The monastery ruins were one of the stops on the itinerary of Pope John Paul II during his visit to Ireland in 1979.