The Wonderful Barn near Leixlip, Ireland
Built in 1743 on the edge of the Castletown estate (also famous for the Conolly Folly which rests on the property) there is some debate over the original intended purpose of the barn. Some have speculated that it may have been used as a dovecote, a place for birds to nest. Doves were considered a delicacy in the 1700s especially when other game was out of season.
Others argue that because of the unique holes drilled through each of the floors the most likely use of the barn was as a granary. This would make sense as in the years preceding its construction several famines ravished Ireland. The barn could have been used to store extra grain in case of times of need. Additionally, the barn bares a striking resemblance to an Indian rice store, which may be where the inspiration for the initial design came from.
Another possibility is that the barn, much like the Conolly Folly, was constructed as a public works program meant to put destitute farmers who had been hurt by the famine back to work.
Interestingly, the staircase scales the exterior of the building, winding around the circumference as it travels upward. This architectural anomaly gives the entire building a slightly corkscrewing effect, as if there were a very slight optical illusion at work. The staircase ends on a flat roof, surrounded by a parapet that furthers the medieval motif of the entire building. (atlasobscura.com)