Many of the current buildings date from the 18th century, though a castle has stood on the site since the days of King John, the first Lord of Ireland.

After the signing of the Anglo-Irish Treaty in December 1921, the complex was ceremonially handed over to the newly formed Provisional Government led by Michael Collins.

Upon the formation of the Irish Free State in December 1922, the castle temporarily assumed the role of the Four Courts, the legal complex badly damaged during the Civil War; this arrangement would last for a decade.

[4] Largely complete by 1230, the castle was of typical Norman courtyard design, with a central square without a keep, bounded on all sides by tall defensive walls and protected at each corner by a circular tower.

Sited to the southeast of Norman Dublin, the castle formed one corner of the outer perimeter of the city, using the River Poddle as a natural means of defence along two of its sides.

In January 1592, Red Hugh O'Donnell and brothers Art and Henry O'Neill escaped from the castle after a period of imprisonement.

Once free of the castle, Henry O'Neill went his own direction and returned safely to Ulster,[5][6] whereas O'Donnell and Art, alongside a guide sent to help them, continued south to the rural valley of Glenmalure, a rebel stronghold where they knew they would find safety.

[11] In 1764, English traveller John Bush wrote: "The Castle, as it is called from its having been the situation of one, I suppose, of which at present there are very few remains, is the residence of the lord lieutenant when in Ireland, but has very little of grandeur in its external appearance besides the large square court-yard, which it encloses.

[12] United Irishmen General Joseph Holt, a participant in the 1798 Rising, was incarcerated in the Bermingham Tower before being transported to New South Wales in 1799.

In 1884 officers at the Castle were at the centre of a homosexual scandal incited by the Irish Nationalist politician William O'Brien through his newspaper United Ireland.

Suspicion fell upon the Officer of Arms, Sir Arthur Vicars, but rumours of his homosexuality and links to socially important gay men in London, may have compromised the investigation.

[14] At the very beginning of the Easter Rising of 1916, a force of twenty-five Irish Citizen Army members were able to seize the entrance and guard room of the Castle before reinforcements for the small garrison arrived.

On the night of Bloody Sunday in 1920, three Irish Republican Army members Dick McKee, Conor Clune and Peadar Clancy, were tortured and killed there.

As President of the Executive Council, Éamon de Valera received credentials there from newly arrived ambassadors to Ireland on behalf of King George V in the 1930s.

The State Apartments, located in the southern range of buildings of the Upper Yard, contain the rooms formerly used by the Lord Lieutenant for personal accommodation and public entertaining during the Castle Season.

[19] Today these richly decorated rooms are used by the Irish government for official engagements including policy launches, hosting of State Visit ceremonial, and the inauguration of the president every seven years.

The banners and hatchment plates of the knights who were living at the time when most of Ireland gained independence as the Irish Free State, in December 1922, remain in place.

Largely destroyed by fire in 1941, the room was reconstructed with minor modifications in 1964–1968 by the OPW, making use of salvaged and replicated furnishings and fittings.

The last dignitary to stay in the royal bedrooms was Prime Minister Margaret Thatcher, who spent a night there with her husband Denis during one of the European Council meetings held in the 1980s.

The most architectural space of the State Apartments, this expressive, deeply modelled corridor, was originally built c. 1758 to the designs of the Surveyor General, Thomas Eyre.

Based on the early 18th-century corridor of Sir Edward Lovett Pearce in the former Parliament House on College Green, it features a marching procession of vaults and arches which were originally top-lit.

The design was denounced by many groups, citing the unsympathetic nature of the four-storey block and the placement, which disrupted the rectangular layout of the Castle.

Dublin Castle has appeared in numerous films including Barry Lyndon, Michael Collins, Becoming Jane and The Medallion, as well as the television series The Tudors, where it doubles as the Vatican in the pilot.