The castle first appears on the 1837 Ordnance Survey map as a rectangular building aligned north to south, surrounded by a small woodland. By the time of the 1913 revised map, it had already deteriorated to merely an outline with a fragment of wall stretching eastward from its southeast corner. Interestingly, no castle appears on the earlier 17th century Down Survey map of Mullingar parish, though we know the lands belonged to Edward and Thomas Tuite in 1641, both described as ‘Irish papists’. Following the Restoration in 1662, the Tuite brothers found themselves opposing Lord Wharton’s claim to their castle, town and lands, suggesting the structure may have been built or rebuilt during this turbulent period.

Today, what remains of Tuitestown Castle consists of three distinct structures within a defended enclosure. The main castle ruins form a rectangular area roughly 15 metres north to south by 7 metres east to west, defined by low, grass-covered stone wall footings with traces of internal dividing walls and evidence of a staircase to the southeast. A collapsed wall, possibly part of a bawn wall or garden feature, creates a linear mound of earth and stone immediately southeast of the castle, where limestone blocks laid in regular courses and bonded with mortar can still be observed. To the northwest stand the footings of a third building, all enclosed within an irregular defensive perimeter marked by wall footings and a substantial fosse, or defensive ditch, along the western and northern sides.

The site reveals layers of occupation and use beyond the castle itself. The northeastern corner of the enclosure rises to form a small, steep-sided mound, whilst the eastern boundary follows a modern drain or stream flowing down to Tuitestown Lough. A causeway entrance pierces the northern defences, and the surrounding fields contain a complex network of old banks and fosses that likely represent the castle’s associated field system. Cultivation ridges and other earthworks visible in aerial photography paint a picture of a once-thriving settlement, now returned to pasture but still readable in the landscape’s subtle undulations and mounds.