Killeen Castle (Irish: Caisleán Chillín), located in Dunsany, County Meath, Ireland, is the current construction on a site occupied by a castle since around 1180. The current building is a restoration of a largely 19th century construction, burnt out in 1981. Killeen was built as one of a pair of castles either side of a major roadway north, the other being the extant Dunsany Castle.
The original structure at Killeen Castle is said to have been a Norman fortification, perhaps wooden, built for the de Lacy magnates, and held from 1172 by the Cusack family, beginning with Geoffrey de Cusack. The stone castle was built by Geoffrey de Cusack around 1181. The date is carved above the doorway.
An early recorded description of the castle and its interior reads - The date is Aug 1st (the feast of St. Peter's Chains). As we approach the castle we are faced by four tall battlemented towers with five storeys of slit openings linking the curtain walls of the building. The castle is set on a slight mound. We enter by a steep wooden stairway, and find ourselves, having passed through the considerable thickness of the wall from the narrow doorway, into the Great Hall on the first floor. Rushes cover the stone flags, and besides the usual furniture, such as a trestle-table, benches and the straight-backed, carved, oaken armchair of the Lord of the Manor, we note on our left a heavy green and white curtain covering one wall of the Hall. Opposite us with its sloping stone hood is the fireplace with logs burning in the grate. The right hand wall is hung with the Lord's war harness, his morion, hunting trophies and feathered lure used in falconry. It is a costly piece with a perch and gilt borders.
In such surroundings the de Cusacks Lords of Killeen lived, made war, and expanded their fiefdoms for 225 years until the castle passed to the Plunketts through the marriage of Lady Joan de Cusack to Christopher Plunkett of Rathregan in 1399.
The first Plunkett to hold the castle, Sir Christopher, became the first Baron Killeen, and divided his estate between his eldest two sons, the second son taking possession of sister castle, Dunsany, and later becoming the first Lord Dunsany. The elder branch continued as Barons of Killeen, and later Earls of Fingall. The third, Sir Thomas Fitz-Christopher Plunket married heiress Mary Ann Cruice of Rathmore, daughter of Sir Christopher Cruice of Cruicetown, Moydorrah and Rathmore Castle - a crucifix in their honour is located on the demense. The fourth and sixth sons founded other landed houses. Dunsoghly Castle, one of the few intact fifteenth-century castles in Ireland, was built by the family of Sir Robert Plunket, the fourth son, between 1450 and 1480. An additional title, as Baron Fingall, in the United Kingdom peerage, was acquired in 1831. While the titles survived, the Killeens were the premier Catholic peers of Ireland.