This intimidating but magnificent structure built on the orders of King John of England in the 13thcentury, was the seat of British rule from 1204 to 1922 when Ireland became independent. It is also where the Minister for Justice and Equality signed the historic order establishing same-sex marriage in Ireland. Visitors can explore a notable collection of Asian and Middle Eastern Art at the library, tour the Garda Museum of the Irish police force or creep through the crypt in the Royal Chapel.