The monastery of Clonmacnoise was founded in 544 by St. Ciarán from Rathcroghan. The large site of the former monastery includes the ruins of a cathedral and seven churches. There are two round towers and three high crosses left. Clonmacnoise was a very famous religious and cultural centre in Medieval times. In the 12th century the site began to decline due to a variety of reasons. In 1552 English troops destroyed Clonmacnoise. Only the perimeter stone of this church remained.