This strategic location at the crossroads of four ancient provinces; Munster, Meath, Leinster and Connacht; made it a natural meeting place for centuries of Irish power brokers. St Brendan supposedly founded a monastery here in the 6th century, which grew into one of the most prestigious foundations in St Columcille’s federation of churches. The monastery’s influence was such that it hosted significant synods in 697 and 1174, drawing kings and churchmen from across Ireland to this border territory of Eile in Munster.

The Anglo-Normans recognised Birr’s importance when they built a castle here by 1207, though their hold proved temporary, lasting only until around 1315. By the mid-14th century, the O’Carrolls of Ely had reclaimed the settlement, and their stronghold, known as the Black Castle, became the principal seat of the ruling dynasty. The O’Carrolls maintained their power base here until 1594, when they sold it to the Butler of Ormond. The real transformation came in 1621 when Laurence Parsons acquired the lands, castle and fortifications as part of the Plantation of Ely O’Carroll, renaming the manor Parsonstown and beginning construction of a new castle for his family.

Today’s Birr Castle represents layers of history built quite literally on top of each other. The current 19th-century structure, designed by John Johnson, incorporates the bones of the 17th-century Parsons castle, which itself stood near the sites of both the 13th-century O’Carroll castle and a 12th-century motte castle. The Black Castle was demolished in 1778 to make way for lawns and parkland, but fragments of the past survive; most notably an internal yew staircase with bold turned balusters that rises through three storeys, a rare survivor from the 17th century. The gatehouse with its two round flanking towers dates from 1620 to 1627, built or rebuilt by Sir Laurence Parsons, whilst a 1668 drawing by Dorothy Parsons shows the house as it once stood: a three-storey, five-bay building with triple gable fronts, tall Jacobean chimney stacks, and L-shaped wings extending from the rear.