Ferns is a historic town in north County Wexford, Ireland. It is 11 km north of Enniscorthy. The remains of Ferns Castle are in the centre of the town. The town is in a civil parish of the same name. Ferns is believed to have been established in the 6th century, when a monastery was founded in 598 dedicated to St Mogue of Clonmore, who was a Bishop of Ferns…Ferns is a historic town in north County Wexford, Ireland. It is 11 km north of Enniscorthy. The remains of Ferns Castle are in the centre of the town. The town is in a civil parish of the same name. Ferns is believed to have been established in the 6th century, when a monastery was founded in 598 dedicated to St Mogue of Clonmore, who was a Bishop of Ferns. The town became the capital of the Kingdom of Leinster, and also the Capital of Ireland when the kings of that southern part of the province established their seat of power there. It was a very large city, but shrank after a fire destroyed most of it. The city stretched all the way past the River Bann, and it is speculated that had it not burned, it would be one of Ireland's biggest cities today. King Dermot MacMurrough founded St. Mary's Abbey as a house of Augustinian canons c. 1158 and was buried there in 1171.