Mountshannon House was a large mansion in Lisnagry, near Castleconnell, County Limerick, built in the mid-18th century.
The estate covered 900 acres (3.6 km2) of land, being bounded to the south by the Mulkear River, the Shannon to the west, and extending some 2 and a half miles along the main Limerick to Castleconnell road from Annacotty to Newgarden.
He was a controversial figure in Irish history, being described variously as a Protestant hardliner, a staunch anti-Catholic, and an early supporter of Union with Great Britain (which finally happened shortly before his death).
This local reputation, however, did not prevent Lord Clare from being known as "Black Jack Fitzgibbon" nationally, apparently because of his hardline opposition to Catholic emancipation.
Images of both the current ruins and the building before destruction can be found on Limerick City's library site: Front of the house [1] Rear of the house, with the conservatory [2] Ruined façade [3] Interior photo of the Library [4] Village by Shannon: the Story of Castleconnell and its Hinterland by Joe Carroll and Pat Tuohy Mountshannon House and the Fitzgibbons: by Carole Gurnett [5] Limerick City Museum [6]