Rappa Castle, Medieval castle ruins in Ballina, Ireland.

Rappa Castle is a castle ruin in Ballina featuring a three-story center block with four bays and two-story wings on either side. The structure is marked by high-pitched gable-ended roofs and tall chimneys that speak to its original status as an important manor house.

Rappa Castle was held by the Bourke family and granted to a Cromwellian soldier named Crofton. In the 17th century William Knox of Castlerea (born 1630) married a Crofton of Rappa, and the house stayed with the Knox family until the 1920s. Francis Knox, born 1726, married Mary Gore, heiress of Rappa, in 1761 and became High Sheriff of Mayo; the estate passed to his son Annesley Gore Knox in 1818.

The Knox family shaped life in the region over generations, and their influence was visible in local administration. The castle served as the center of a large estate that structured the surrounding communities.

The castle ruins sit along the N59 route near Ballina and are relatively easy to reach. Exploring the site typically takes about 30 minutes, making it suitable for a brief visit alongside other attractions.

The castle is a listed protected structure, and the Gillespie family, who took over after the Knoxes left following the Irish War of Independence, built a new house in front of it. That house was lived in until 2001, while the ruined castle stands behind it.