Dublin Castle was the seat of the British Government until 1922. Over the centuries, it has been a place of historical importance and varied functionality. Originally built in the 18th century, its legacy dates back to the days of King John, being a symbol of British administration in Ireland during the Lordship of Ireland, the Kingdom of Ireland and the United Kingdom of Great Britain and Ireland.

The castle has served as a royal residence and seat of government, including the Viceroy's Apartments and the offices of the Chief Secretary for Ireland. It has also housed parliament, the courts and a military garrison. During the British occupation, the term "Castle Catholic" was used derogatorily for those Catholics perceived as British collaborators.

In 1907, the theft of the Irish Crown Jewels inside the castle captured public attention. During the Anglo-Irish War, the castle was a focal point of the conflict. After the creation of the Irish Free State in 1922, it lost its governmental function and was temporarily used as a judicial seat before becoming a venue for state ceremonies.

Today, Dublin Castle is a tourist attraction and conference center, maintained by the Office of Public Works. Recent redevelopment has turned it into a venue for events and meetings, including European Council summits during Ireland's presidencies of the European Union. It also houses the offices of the Tax Commissioners and is accessible to the public for tours, except during official events.