The Cathedral Church of St Mel is the cathedral church of the Roman Catholic Diocese of Ardagh and Clonmacnoise, located in the town of Longford in Ireland. Built between 1840 and 1856, with the belfry and portico as later additions, it has been considered the "flagship cathedral" of the Irish midlands region, Longford's "landmark building" and "one of the finest Catholic churches in Ireland". The cathedral is dedicated to Saint Mél, who came to Ireland with Saint Patrick and who was ordained bishop at Ardagh, County Longford.