Along with 18th century Damer House and gardens, the castle forms part of Roscrea Heritage Centre.

Construction was overseen by the Justiciar, Henry of London, and formed part of John's efforts to solidify his conquest of Ireland, particularly the midlands and southern counties.

[8][9][10][11][12] The original wooden castle was destroyed in the late 13th century and replaced with the current stone structure.

While it does not have a keep, the main residence is a three-storey rectangular gate building to the north, complemented by two three-quarter round towers, one to the southwest and one to the southeast.

The original gate building is dated to around 1280 but the current stone structure was built by the 4th Earl of Ormond in the 15th century.

In the 17th century, a second floor living area was added to the building including a pointed groined vault, three bays, lancet windows, a garderobe, a chimney stack, a large hooded dog-tooth capital fireplace on the southern wall, and crow-stepped gables.

Although recognised as one of the few examples of pre-Palladian architecture in Ireland, Damer House was due to be demolished in the 1960s, with suggestions that it be replaced by a swimming pool or a bacon factory.

It was eventually saved after a campaign by Desmond Guinness and the Irish Georgian Society, which took out a lease on the house in 1973.

Restoration was completed in the 1990s by the national heritage service Dúchas with additional funding from Bord Fáilte and £100,000 from the Government Policy for Architecture.