Castlereagh House, Demesne, Co. Roscommon

This medieval stronghold saw considerable action during the turbulent late 15th and early 16th centuries, when Irish lords and Anglo-Norman earls regularly fought for control of strategic fortifications. In 1499, Garret Mór FitzGerald, the powerful Earl of Kildare, captured the castle using ordnance; a significant achievement given that artillery was still relatively uncommon in Irish warfare at the time.

The castle remained a coveted prize for decades. Garret's son, Garret Óg, the ninth Earl of Kildare, seized it again in 1526 whilst acting on behalf of O'Connor Roe. However, their triumph was short-lived; O'Donnell successfully captured and destroyed the fortress just a year later in 1527. The resilient structure must have been quickly rebuilt, as O'Connor Roe and MacDermott later mounted an ambitious six-week siege against it that same year, even employing a siege engine in their assault. Despite their considerable efforts, the castle held firm and the besiegers were forced to withdraw.

Following the Cromwellian conquest of Ireland in the 1650s, the lands passed to Captain Theophilus Sandford, forming the nucleus of what would become the Sandford estate. The old castle became associated with Castlereagh House, though both structures have long since vanished from the landscape. The house itself was demolished in the 1960s, and today no trace remains of either the medieval fortress that witnessed so much conflict or the later manor that succeeded it.