Though the original fortress was thought to have been replaced by Ballycarty House, built for the Nash family between 1765 and 1770, recent research suggests the castle’s ruins may still survive northeast of the later mansion, possibly near an old bridge over the River Lee. Local historian Bill Jehan notes that parts of Ballycarty watermill’s ruins appear robust enough to have served defensive purposes, raising the intriguing possibility that the old castle was later adapted into a mill.

The castle played a pivotal role during the 1641 Rebellion, serving as a refuge for approximately three hundred Protestant men, women and children who sheltered there from December 1641 until November 1642. According to depositions from the period, the castle was surrendered without siege by its constable, Robert Blennerhassett, to Colonel Donnell Og McCarthy of Killarney, against the wishes of the warders. The depositions paint a vivid picture of life during the rebellion: Edward Thorne, the castle’s miller, ground corn for rebels besieging Tralee with Blennerhassett’s permission, whilst witnesses recorded oath;taking ceremonies within the castle walls as local gentry swore allegiance to the rebel cause.

By 1884, observers described “a small square tower on Ballycarty”, likely a Geraldine fortress predating 1584, along with extensive ruins of a castle or mansion with a bawn southwest of Ballyseedy House. After Ballycarty House was burnt by Republicans in January 1923 during the Civil War, most ruins were cleared when a new house was constructed in 2009, though it incorporated some 18th century elements. Today, visitors can still explore the mysterious ruins near the River Lee, where the boundaries between castle, mill and mansion blur into Kerry’s contested past.