The lands here have a long history, originally known as Machernevin or Maghairnidhe, held alongside Ballymagir by Alina de Heding in 1247 under two knights’ fees from William de Vallence. By 1260, the property had passed to the Devereux family, likely through marriage, and remained in their hands for centuries. A memorial stone, now housed in nearby Adamstown House, once proclaimed the castle’s founding date above the gateway of its protective bawn wall.

The four-storey tower house, measuring approximately 9.35m by 8.95m, showcases classic defensive features of its era. Its granite-quoined walls rise from a base batter, with the original pointed entrance on the northeast wall showing evidence of a yett, a heavy iron gate typical of Scottish and Irish fortifications. Inside, a vaulted ground floor bristles with gun loops at each corner, whilst mural stairs protected by a murder hole lead to upper floors featuring fireplaces, tall windows with rounded heads, and additional defensive positions. Though the structure survived intact for over 400 years, the north corner collapsed in February 1961, leaving the remaining walls to tell their story.

Archaeological evidence reveals the tower house sat within an impressive defensive complex; a bawn wall enclosing approximately one acre once stood 20 feet high with corner towers, creating a rectangular fortified area roughly 70m by 60m. According to the Civil Survey of 1654-6, Nicholas Devereux owned most of Adamstown parish along with what was described as a ‘faire castle’, though by the 19th century, much of this land had transferred to the Downes family. Today, visitors can still trace the outline of these defensive walls as grass-covered scarps surrounding the tower, offering a tangible connection to the castle’s role in protecting its inhabitants during Ireland’s turbulent medieval and early modern periods.