Birr
- ''This article is about Birr, the town in Ireland. For alternative meanings see: Birr (disambiguation).
A main feature on the grounds of the castle is the great telescope of the third Earl of Rosse, an astronomical telescope with a 72-inch reflector which was, until 1917, the largest telescope in the world.
Flowing past Birr, the Camcor River flows into the Little Brosna which, in turn, flows into the River Shannon.