Crom castle. Crom castle can be found nestled along the banks of the Lough Erne in County Fermanagh in Northern Ireland. The estate in which the castle is set is measured as being approximately 1,900 acres. Like many of the grand estates which can be found within the county of Ulster, the house at Crom was erected by a Scottish planter just towards the end of the 1600s. In the year 1611, as part of the plantation of Ulster, Michael Balfour, the Laird of Mountwhinney, constructed a house on the Lough shore opposite Inishfendra Island. Following the usual pattern for a plantation castle, The old castle at Crom was built of lime and stone and was enclosed within a bawn.