Birr Castle dates back to medieval times.
There was a castle here built on a motte by the Anglo Normans. The gate tower of this led into the castle bawn and is now the centre of the present building. This central gate passage with its 12’ walls can be seen in the lower floor of the present building.
The castle or fortress of Birr was re occupied by the O’Carrolls who held it until the 1580s when it was sold to the Ormond Butlers. In 1620 the now ruined castle was granted to the Parsons family by James I. Rather than occupy the tower house of the O’Carrolls they preferred to turn the Norman gate tower into their ‘English House’, building on either side and incorporating two flanking towers. Sir Laurence Parsons did a large amount of building and remodelling including, probably, the building of the two flanking towers, before his death in 1628. This is all accounted for in our archives.
The castle survived two sieges in the 17th century, leaving the family impoverished at the beginning of the 18th century and little was done to the 17th century house. However at some time towards the end of that century, or at the beginning of the 19th century, the house, which had always faced the town, was given a new gothic facade, which now faced the park. The ancient towers and walls on this, now the park side of the castle, were swept away, including the Black Tower (the tower house) of the O’Carrolls, which had stood on the motte. Around 1820 the octagonal Gothic Saloon overlooking the river was cleverly added into the space between the central block and the west flanking tower.
After a fire in the central block in 1836 the centre of the castle was rebuilt, ceilings heightened, a third story added and also the great dining room. In the middle of the 1840s to employ a larger work force during the famine, the old moat and the original Norman motte were also flattened and a new star-shaped moat was designed, with a keep gate. This was financed by Mary, Countess of Rosse. At this time the great telescope was built.
The final work on the castle was done in the 1860s when a square tower at the back of the castle on the East side was added. This now contains nurseries on the top floor which have a great view over the town.