When historian Davies examined the property in 1948, he discovered that the house sits atop massive foundations and vaulted chambers that likely date back to a 17th-century castle. These substantial remains suggest that Ashgrove was once home to a fortified structure of considerable importance, built during Ireland’s turbulent plantation period when defensive architecture was essential for survival.

The site reveals more of its defensive past to the west of the main house, where portions of what appears to be a bawn wall still survive. This section of wall, measuring roughly 0.6 metres thick, features a distinctive row of arched recesses flanked by engaged masonry columns; architectural details that speak to both the defensive and aesthetic considerations of 17th-century Irish fortifications. Bawns were walled enclosures that protected castle households, their livestock, and crops from raids, and finding remnants of one at Ashgrove provides valuable insight into how these plantation-era settlements were organised.

While the current house may look like a typical Georgian country residence, these archaeological features remind us that Ashgrove has witnessed centuries of Irish history. The transition from fortified castle with protective bawn to elegant country house mirrors the broader changes in Irish society as the country moved from the violence of the 17th century towards the relative stability of the 18th century, when landowners could finally afford to prioritise comfort and style over defensive capabilities.