Smarmore Castle, Medieval castle in County Louth, Ireland

Smarmore Castle is a medieval fortress in County Louth featuring a central tower house with additional structures built in the 18th century. The buildings form a complex that blends an earlier defensive core with later residential additions.

Smarmore Castle was first recorded in 1320 as the seat of the Taaffe family, who came from Pembrokeshire in Wales. They lived there until the 1980s, when the castle was sold and turned into a guest house. A tower house was built around 1320, and further buildings were added between 1730 and 1750. In 2015 the British addiction treatment centre Castle Craig bought the castle, and the Smarmore Castle Private Clinic opened in 2016.

The name Smarmore links to an ancient Irish legend about a cattle raid set in this region. This old story remains part of the local cultural identity today.

The castle operates today as a private rehabilitation facility offering medical treatment and therapy programs. Visitors should check in advance since the site may have limited access or specific visiting arrangements.

The name Smarmore is traced to Táin Bó Cúailnge, the Cattle Raid of Cooley, an early Irish epic set in this part of County Louth. The castle's Irish name is Caisleán Smearamair.