The house was originally known as Kildare House after James Fitzgerald, the Earl of Kildare, who commissioned it to be built between 1745-47. Fitzgerald set out to create the stateliest of Dublin Georgian Mansions to reflect his eminent position in Irish society.
It is told that the Earl had said that fashion would follow in whatever direction he led.
In succeeding, he caused an unfashionable area of the city to become a desirable one.
On becoming the Duke of Leinster in 1776 (Dublin and Kildare are in the province of Leinster) the house was renamed Leinster House.
The designer of Leinster House was the architect Richard Cassels (or Castle), who was born in Hesse-Cassel in Germany about 1690. The design is characteristic of buildings of the period in Ireland and England.
It has been claimed that it formed a model for the design of the White House, the residence of the President of the United States. This claim may have its origins in the career of James Hoban, who in 1792 won the competition for the design of the White House.
Hoban was an Irishman, born in Callan, County Kilkenny in 1762, and studied architecture in Dublin, and consequently, would have had an opportunity of studying the design of Leinster House.
A supporter of the United Irishmen, who advocated complete separation of Ireland from England, Lord Edward Fitzgerald, fifth son of the first Duke of Leinster, was arrested shortly before the insurrection of May 1798 and died of wounds received during his capture.
No doubt it was beyond his wildest dreams that many years later the Irish Parliament would be located in his family home.
In 1815, Augustus Frederick, the third Duke of Leinster, sold the mansion to the Royal Dublin Society (RDS) for £10,000 and a yearly rent of £600 which was later redeemed.
The purpose of the society was to improve the wretched conditions of the people. Many important public institutions of the present day owe their origins to the RDS:
The Society made extensive additions to the house, most notably the lecture theatre, later to become the Dáil Chamber.
A number of historic events took place in Leinster House. The first balloon ascent in Ireland was made in July 1783 by Richard Crosbie from Leinster Lawn.
The Great Industrial Exhibition was opened on Leinster Lawn on 12 May 1853.
After the establishment of the Irish Free State in 1922, the Government secured a part of Leinster House for parliamentary use. The entire building was acquired by the State in 1924.
Today, Leinster House is the seat of the two Houses of the Oireachtas (National Parliament), comprising Dáil Éireann (the House of Representatives) and Seanad Éireann (the Senate).