Clonalis House, Victorian stately home in Castlerea, Ireland

Clonalis House is a mass-concrete manor built in 1878 to Frederick Pepys Cockerell's design, mixing Italianate and Queen Anne elements. It stands at Castlerea, County Roscommon, on the site of an earlier house repeatedly damaged by flooding, and remains the home of the O'Conor Don.

The house was built in 1878 on a site where an earlier structure had suffered from flooding problems. The residence was created by the O'Conor family, whose roots trace back to the medieval kings who once ruled Connacht.

The O'Conor Don are descendants of Cathal Crobhdearg Ua Conchobair, King of Connacht, brother of Ruaidrí Ua Conchobair, the last High King of Ireland. The family's library and archives, still kept at Clonalis, hold some 100,000 volumes. The house was occupied by the IRA and then shelled and captured by Free State forces during the Civil War.

Visitors can arrange guided tours to walk through the rooms and see how the family lived while exploring the landscaped grounds around the property. Booking in advance is recommended as tours are organized at set times throughout the day.

The family maintains a private library containing over 100,000 volumes, an unusually large collection for a private home. These books and manuscripts span multiple centuries and reveal the wide-ranging interests the family pursued across generations.