Dating back to 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. Restoration work is ongoing; look for the ruined great hall with its early 13th-century windows.
Book tours 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 grounds of the Augustinian priory.
