Dating from around 1200, this picturesque Norman ruin changed hands several times before being entirely wrecked by Cromwell's troops in 1657, by which time its strategic importance had slipped away. Highlights include the great hall with its early-13th-century windows, and the huge kitchen and bakery.
Tours must be booked through the Adare Heritage Centre. When tours aren't on, you can view the castle from the busy main road, or more peacefully from the riverside footpath or the Augustinian Priory grounds.