Dublin Castle was built between 1208 and 1220 and was used as the headquarters by the British government of Ireland until it gained independence in 1922. The current building dates back to 18th century because it was rebuilt after having been destroyed by a fire.
Today, elections and official state events are held at Dublin Castle. There are also guided visits of the building showing the State Apartments which are used as the residential and public quarters of the Viceregal Court, the Chapel Royal and the Viking defence bank in the Undercroft.
Dublin Castle houses the Garda Police Museum which is where you will see the Throne Room and the Normandy Tower (1226). The Dubhlinn Gardens are also worth a visit and have been located behind the castle since 1680.
Dublin Guide | Historical buildings in Dublin