Birr Castle is located in the town of Birr. It is currently occupied by the Earl of Rosse and as such residential areas of the castle are not publicly accessable.
The castle grounds are also home to Ireland’s Historic Science Centre, a museum of Ireland’s historic scientists and their contributions to astronomy and botany.
Birr Castle was built sometime around 1170 and from the 14th to the 17th century the O’Carroll family ruled from here over an area known as “Ely O’Carroll”.
Following the passing of Sir Charles O’Carroll, Sir Laurence Parsons was granted Birr Castle as well as its 1,277 acres (5.2 km2) of land in 1620, Parsons main contribution in terms of construction was to add “Flankers” diagonally at either side of the gatehouse, a feature which survives to this day.
The Castle was inherited by youngest son William following his fathers death and during the Irish Rebellion of 1641, Birr Castle was the scene of a siege for some 15 Months by Catholic Forces.
Sometime after a later descendant Laurence Parsons, 2nd Earl of Rosse, further made upgrades to the Castles Architecture by both increasing the height as well as change certain areas of the Castle for the more Gothic Theme.
His son, William Parsons, 3rd Earl of Rosse, built the Great Telescope of Birr in 1845 which in its day was the largest and most powerful telescope on earth.
The Scientific Tradition carried on to the next generation of Parsons when Lawrence Parsons, 4th Earl of Rosse was noted for measuring the heat of the moon. Though after his death that’s as far as the Scientific Tradition would go at that point and the Great Telescope fell into disrepair and would not be restored till the late 1990s.