This five-storey fortress, built from roughly coursed sandstone rubble, served as a principal stronghold of the Ormond Butlers from the early 14th century onwards. The de Valle (Wall) family originally held Kilcash until it passed to the Earl of Ormond between 1538 and 1545, with the manor appearing in the 9th Earl’s will of 1545. From 1639 to 1758, it became the seat of a junior branch of the Butler family, who transformed it into a comfortable residence complete with a great hall hung with paintings and parkland stocked with deer.

The tower house itself measures 13.1 metres north to south and 9.55 metres east to west, featuring distinctive defensive elements including machicolations above the entrance and at the northwest and southeast corners. Entry through the western wall leads to a small lobby with a murder hole overhead, alongside a vaulted guard room that once protected the entrance with gun loops. The interior reveals extensive 17th-century modifications, including a two-storey house with attic built against the western wall and another structure added to the northern side. Each floor showcases different architectural features; the first floor contains a large fireplace with polished limestone surrounds, whilst the upper floors feature multiple windows, including elegant two and three-light openings with hood mouldings, and elaborate fireplaces that speak to the castle’s domestic refinement.

Following the Civil Survey of 1654-6, which recorded the castle as having its roof and lofts burnt but still maintaining a bawn with thatched cabins, the building continued in use well into the 18th century. When John Butler became the 15th Earl of Ormonde in 1758, the castle’s fortunes declined, and around 1800, the 18th Earl sold its materials to James Power, a merchant from Carrick-on-Suir. Today, though the wooden floors have long since vanished, the structure retains remarkable details including remains of exterior render with decorative plaster string courses featuring zigzag patterns, spiral stairs in the northeast angle, mural chambers in the corners, and three tall chimney stacks on the western wall, offering visitors a compelling glimpse into both the military and domestic life of medieval Irish nobility.