Birr Castle (Irish: Caisleán Bhiorra) is a large castle in the town of Birr in County Offaly, Ireland. It is the home of the seventh Earl of Rosse, and as such the residential areas of the castle are not open to the public, though the grounds and gardens of the demesne are publicly accessible.
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.
There has been a castle on the site since 1170, and from the 14th to the 17th century the O'Carroll family ruled from here over an area known as "Ely O'Carroll".
After the death of Sir Charles O'Carroll, Sir Laurence Parsons (died 1628) was granted Birr Castle and 1,277 acres (5.2 km2) of land in 1620. Parsons engaged English masons in the construction of a new castle on the site. This construction took place, not on the site of the O'Carroll's Black Tower (since disappeared), but at its gatehouse. "Flankers" were added to the gatehouse diagonally at either side, giving the castle the plan it retains today.
Birr may refer to:
Birr is a municipality in the Swiss canton of Aargau and the capital of Brugg (district). The village lies halfway between Lenzburg and Brugg. Birr has grown with its neighbour Lupfig into a conurbation.
Birr is known as one of the places where the Swiss educator Johann Heinrich Pestalozzi established new standards in education. His gravesite in Birr is listed as a heritage site of national significance.
While a few artifacts from the Roman and Alamanni eras have been found in Birr, there was no known settlement. Birr is first mentioned in 1270 as Bire. Throughout the High Middle Ages the village belonged to the Habsburgs. The rights to rule the village went to Königsfelden Abbey at Windisch in 1397 and 1411. After the secularization of the monastery in 1528 those rights transferred to Bern.
The chapel, which was a subsidiary of Windisch, became a parish church during the Reformation. This parish includes; Lupfig, Birrhard, Scherz, Schinznach-Bad and Brunegg. The current reformed church was built in 1662 by Abraham Dünz.
Birr, a division of King's County, was a UK Parliament constituency in Ireland, returning one Member of Parliament 1885–1918.
Prior to the United Kingdom general election, 1885 and after the dissolution of Parliament in 1918 the area was part of the King's County constituency.
This constituency comprised the south-western part of King's County now known as County Offaly. It consisted of the baronies of Ballycowan, Ballyboy and Eglish, Ballybritt, Clonlisk and Garrycastle.