The castle's history stretches back to the mid-13th century when the Butler family held sway here, before the property passed through marriage to the Nugents in the mid-15th century. By the 1600s, the Sherlock family had taken ownership, and they held onto it through turbulent times, including damage from a fire during the 1798 Rebellion.

The tower itself is a substantial structure, measuring 12.2 metres by 10.2 metres, rising three storeys high with its original defensive batter still visible on the northeast wall. What makes Butlerstown particularly fascinating is how it showcases both medieval defensive architecture and 19th-century gentrification. When the Sherlocks sold the castle to a Mr Backas in the early 1800s, he transformed it from a stark defensive structure into a more comfortable residence, building an adjoining house against the southwest wall and modernising the interior. The original spiral staircase at the western angle, which once connected all floors, was partially removed during these renovations, though portions remain to connect the upper levels.

Inside, the castle reveals its dual nature as both fortress and home. The ground floor features altered embrasures; one has been cleverly converted into a fireplace and oven, whilst the loft boasts a barrel-vaulted ceiling and mural passages typical of medieval construction. The upper floors show more obvious signs of modernisation, with updated window embrasures and the addition of ornamental turrets and parapets that give the castle its current romantic appearance. Intriguingly, aerial photographs have revealed mysterious linear cropmarks in the field northwest of the tower, possibly remnants of ancient drainage systems or field boundaries, adding another layer to the site's archaeological significance.