The ruins of the mediaeval Killesher Church lie about 2.6 miles south-east of Blacklion. The ruins sit on a hillside in the south-west of County Fermanagh, between Blacklion and Cladagh Bridge, very close to the Hanging Rock and overlooking both the Gortatole Outdoor Education Centre and Lower Lough Macnean. The current ruins sit on an Early Christian ecclesiastical site associated with St. Lasser or St. Lasair. The modern Parish of Killesher in both the Diocese of Kilmore and the Diocese of Kilmore, Elphin and Ardagh is named after this ancient site.