This vanished fortress once commanded views over the river crossing alongside its neighbouring church, both depicted on Sir William Petty's Down Survey maps from 1654 to 1657. The survey's terrier paints a melancholy picture of 17th century Tankardstown: 'a ruined Castle and Church with some ruined Houses', suggesting the settlement had already seen better days by the time the surveyors arrived.

The castle's history is tied to Thomas Hovenden, recorded in 1641 as an 'Irish Papist' who held 565 acres of profitable land and 11 acres of unprofitable land in Tankardstown. His castle formed part of a defensive network; another castle site lies about a quarter mile to the south, and together they appear to have been strategically placed to control passage over the River Barrow. Today, the levelled castle site sits 75 metres west of the river, with St. Thomas's Well 135 metres to the southeast and the ruins of Tankardstown church and its graveyard 175 metres to the south.

While the castle itself has completely disappeared from view, leaving no visible surface remains, its presence lingers in the historical record and in the landscape's memory. The nearby church ruins and graveyard still mark the spot where this medieval community once thrived, and St. Thomas's Well continues to bubble away, a tangible link to the area's past. These scattered remnants, noted by historians O'Hanlon and O'Leary in 1907, tell the story of a once vital settlement that controlled an important river crossing in Queen's County, as Laois was then known.