The Round Tower, Devenish, Co Fermanagh Devenish Monastic Site is considered to be the most important of Lough Erne's many island church settlements. Devenish was founded in the 6th century by St Molaise.It was raided by Vikings in 837 and burned in 1157. This is one of the finest towers in Ireland and they were thought to have been used to store valuable relics as well as a belfry.The entrances were always at first floor level to enable the monks to raise the ladder in times of attack.