Dublin Castle (Irish: Caisleán Bhaile Átha Cliath) off Dame Street, Dublin, Ireland, was until 1922 the seat of the United Kingdom government's administration in Ireland, and is now a major Irish government complex. Most of it dates from the 18th century, though a castle has stood on the site since the days of King John, the first Lord of Ireland. The Castle served as the seat of English, then later British government of Ireland under the Lordship of Ireland (1171–1541), the Kingdom of Ireland (1541–1800), and the United Kingdom of Great Britain and Ireland (1800–1922).

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.[1]

The castle today is a major tourist attraction and conferencing destination. The building is also used for State dinners (the most recent being for Queen Elizabeth II in 2011) and most significantly, the inauguration of the presidents of Ireland.