Roman Catholic Diocese of Ardagh and Clonmacnoise Roman Catholic Diocese of Ardagh and Clonmacnoise The Diocese of Ardagh and Clonmacnoise () is a Roman Catholic diocese in Ireland. The diocese is entirely within the Republic of Ireland and contains most of counties Longford and Leitrim, with parts of counties Cavan, Offaly, Roscommon, Sligo and Westmeath. The main towns in the diocese are Athlone, Ballymahon, Carrick-on-Shannon, Edgeworthstown, Granard and Longford. The union of the sees of Ardagh and Clonmacnoise, which had been proposed in 1709, was carried into effect following the death of Stephen MacEgan, Bishop of Meath on 30 May 1756, who had been administering the see
County Cavan springs near Bailieborough; the River Annalee which flows from Lough Sillan and joins the Erne; and the Cladagh river which rises from Cuilcagh and flows into Fermanagh. The Glyde and the Owenroe also source in Cavan. Cavan is known as 'The Lakeland County' and is reputed to contain 365 lakes. At , Lough Sheelin is the county's largest lake; it is situated in the south of the county and forms a three way border on its waters between counties Meath, Westmeath and Cavan. A large complex of lakes form in the north and west of Cavan into designated Specially Protected