The Wonderful Barn is a corkscrew-shaped building on the edge of Castletown House Estate, formerly of the Conolly family, in Celbridge, County Kildare, Ireland.

Flanked by two smaller dovecote towers, the barn was built with the stairs ascending around the exterior of the building.

[1] The barn was built in 1743 on the Leixlip side of the Castletown Estate.

[2] Several purposes are suggested for the unique structure: The construction project also likely served as a way to keep the local poor employed.

A similar structure known as the Bottle Tower, built in imitation of the Wonderful Barn, is located in Churchtown, close to Rathfarnham.