Situated on a level landscape with the NW-SE Athboy River, sometimes called the Tremblestown River, in its valley c. 120m to the SW. The motte and bailey (ME036-004----) is c. 30m to the NE and the church (ME036-002----) is c. 190m to the NW. The castle is within a designed landscape or field system (ME035-005----) that could relate to the medieval tower house, although it might have been formed during the eighteenth century occupancy.
Robert Barnwall was made the first Baron Trimlestown by King Edward IV in 1461 (O’Reilly 1957, 66). Sir John Barnwall, the third Baron, had interests in Church properties at the Suppression in 1540 (White 1940, 295, 297, 315, 321). According to the Civil Survey (1654-54) Mathias Barnewall, the eight Lord Trimlestown, owned 480 acres at Trimlestown in 1640, and on the premises were ‘one Castle, an ould Church, two Mills, a Weare and a Bridge’ (Simington 1940, 247). He also owned land at Dunlevers (164 acres), Gormanstowne (80 acres) and Oaketowne (82 acres) amounting to almost all the parish (ibid. 247-8), as well as having interests throughout the county. The castle was occupied by Confederate Catholics during the 1640s but surrendered in 1647 to Cromwellian forces under General Jones.
The castle was subsequently developed by adding a wing to the NE with a large SE-facing bay window, but it was a ruin by the 1830s (Lewis 1837, 2, 645; Wilde 1849, 78).The castle was subsequently developed by adding a wing to the NE with a large SE-facing bay window, but it was a ruin by the 1830s (Lewis 1837, 2, 645; Wilde 1849, 78). Although the Barnwalls were Roman Catholic they managed to retain the core of the Tremblestown Estate, but seem to have abandoned the castle by the end of the eighteenth century. Robert, the twelfth Lord Trimlestown (d. 1779) used his position to promote Catholic causes but a proposal that Catholics should be able to serve in the army was rejected in 1762. His sons, Thomas the thirteenth Lord Trimlestown and Mathias, became Protestants. It is not known when the Barnwalls severed their connection with Tremblestown, but they also had property at Roebuck, Co. Dublin. The line is dormant since the death of the sixteenth baron in 1879.
This is a rectangular three-storey house with a large projecting tower at the W angle and a smaller one at the S angle, but the building had been largely altered in the eighteenth century and the W tower appears to have been constructed then, although it might be on the site of an older tower. The original doorway is towards the N end of the SE wall, and leads directly to the ground floor (int. dims 15.9m NE-SW; 5.05m NW-SE) with a mural stairs mounting the wall to the S from the entrance. The long NW wall had five embrasures with lights on the ground floor, which are largely either blocked or destroyed, but one was altered into a fireplace. The E angle where it connected with the 18th century wing is destroyed and a stairs tower may have been located here. The first floor is under the vault and was supported by corbels, now largely missing, in the long walls. It was entered by a flat-arched doorway from the mural stairs in the SE wall. A doorway at the S end of this wall accessed the chamber in the S tower, which was probably contains a garderobe. A single large window is inserted into the SW wall and two into the NW wall, but a chimney-flue in the NE wall may be original. At the E angle where it connected with the eighteenth century wing there was a newel stairs, partly supported on an external squinch, but all the steps are removed. The second floor is over the vault, and has two large windows in the NW wall and three in the SE. There are also small fireplaces in the NE and SE walls, but none of these features might be original. The third floor has three windows and a fireplace in the long NW and SE walls and the joists for its floor were set directly into the walls. The only original feature might be a doorway into the S tower, which might have provided access to the wall-walk, but only the housing over this tower survives together with a fourth level of the W tower.
The above description is derived from the published 'Archaeological Inventory of County Meath' (Dublin: Stationery Office, 1987). In certain instances the entries have been revised and updated in the light of recent research.
Compiled by: Michael Moore
Date of revision: 13 July 2016
Amended: 5 July 2019
Description Source: National Monuments Service, Department of Arts, Heritage Regional, Rural and Gaeltacht Affairs.