The castle likely takes its name from Captain Pierce of Tristernagh, a Protestant landowner who held 460 acres in Templeoran parish according to the Down Survey records of the 1650s. By the late 17th century, the property appears to have passed to Andrew Wilson of Shinglis, born around 1640, who would go on to found Wilson Hospital. His 1724 will mentions a mansion house at ‘Piersfield’, suggesting the site remained an important residence well into the 18th century.

Today, visitors to the site will find only subtle earthworks marking where the castle once stood. A sunken rectangular area measuring approximately 24 metres east to west by 8 metres north to south, defined by low grass-covered wall footings, represents all that remains of the structure. Archaeological surveys suggest this was likely a 17th-century rectangular fortified house rather than a medieval square tower house. The castle site occupies the northwest corner of what may have been a larger walled enclosure or bawn measuring roughly 120 metres square, though some reports describe smaller dimensions, possibly indicating different phases of use or partial survival of the original boundaries.

The site has suffered considerably over the centuries. Historical Ordnance Survey maps from 1837 and 1911 show the castle as a rectangular building aligned east to west, with associated field boundaries that have since disappeared. A quarry appears to have destroyed the southern wall, whilst more recently, an access road for a sports field was driven straight through the centre of the castle site, as visible in 2011 aerial photographs. Despite this damage, the earthworks remain legible enough to trace the footprint of this once-prominent Westmeath residence, offering a tangible connection to the Protestant landowning families who shaped this part of Ireland during the turbulent 17th and 18th centuries.