High Quality Content by WIKIPEDIA articles! High Quality Content by WIKIPEDIA articles! The Diocese of Ardagh and Clonmacnoise is a Roman Catholic diocese in Ireland. The diocese is spread over parts of seven counties in the centre of Ireland. It includes almost all of County Longford, half of County Leitrim and parts of counties Westmeath, Offaly, Cavan, Roscommon and Sligo. It covers an area of 941 square miles (2,437 km2). At the end of 1996, the population was 70,748, of which 69,612 were Catholic. It has 64 priests at present, and a total of 41 parishes. The diocese of Ardagh, as distinct from that of Clonmacnoise, with which it is now united, takes its name from the village of Ardagh, now a picturesque village in County Longford.