Donamon, or more correctly, Dunamon Castle (Irish: Dún Iomáin) is one of the oldest inhabited buildings in Ireland and stands on raised ground overlooking the River Suck in County Roscommon.There was a fort here from early times (hence the name Dún Iomáin, fort of Iomán), but the first recorded reference to "Dún Iomghain" is in the Annals of the Four Masters for the year 1154.