Rattin Castle is a dilapidated fortress situated southwest of Kinnegad, in County Westmeath, Ireland. Constructed in the 16th century, it was originally designed as a defensive tower for the surrounding estate. The land was initially held by Hugh De Lacy before being passed down to John D’Arcy.

The ghost of Rattin Castle, appearing as a black dog, is said to appear before the death of any D’Arcy family member. A dispute arose between two brothers over the division of their extensive estate, including Rattin, Clonfad, Hightown (formerly Ballyoughter), Coralstown, Lisnabin, Grangebeg, and the Castle near Raharney. When the elder Darcy passed away suddenly, without finalising the estate’s division, the eldest son claimed all the land, leading to a bitter feud with his younger brother.

Despite attempts by neighboring clans to mediate, the two brothers decided to resolve the conflict through a duel. Seconds were chosen, and on a May morning, the brothers faced off, both skilled swordsmen. After a prolonged battle, the younger brother succumbed to his injuries and died days later at Rattin Castle. The eldest brother inherited the estate but became disliked by neighboring clans, who blamed him for his brother’s death driven by greed.

Years later, the eldest brother took his own life at the Castle of Hightown (or Ballyoughter). The castle has since disappeared, but his ghost is believed to haunt the area to this day. The valley between Rattin Castle and Hightown, known as the Valley of the Black Dog, was often spoken of by the locals in the area.