The 1657 Down Survey map marks this spot in Ballintullagh (Tullystown) with the symbol of a castle, then owned by James Nugent, an English Protestant who held the lands before the tumultuous events of 1641. Today, only the south and west walls of this once imposing structure survive, having been cleverly incorporated into farm buildings constructed sometime after 1700.

The tower house originally measured approximately 6 metres north to south and 4.8 metres east to west internally, likely rising three storeys high. Its defensive features are still visible; rounded corners on the southwest angle and a base batter on the west wall, which stands about 7 metres high with walls between 1.2 and 1.4 metres thick. The ground floor shows typical defensive architecture with no windows, only a niche in the south wall, whilst evidence of a blocked window can be seen at first floor level in the west wall. Later modifications tell their own story, with a fireplace and chimney flue broken through the south wall, cutting across an original window whose single splay still survives.

The surrounding landscape holds further clues to the castle’s original extent. Stone from the tower house found new life in the post 1700 farm buildings, including a distinctive square headed slit window of 15th or 16th century style, carefully reused in one of the agricultural structures. The walled garden west of the tower may incorporate portions of the original bawn wall that once protected the castle complex. Meanwhile, Tullystown House to the north represents a later chapter in the site’s history; an elegant early 19th century residence of two storeys over a basement, featuring three bays with a central breakfront and a fine doorway complete with fanlight and sidelights.