Dublin Castle was the centre of the government of Ireland under English and later British rule. "Dublin Castle" is used metonymically to describe British rule in Ireland. The Castle held only the executive branch of government and the Privy Council of Ireland, both appointed by the British government. The Castle did not hold the judicial branch, which was centred on the Four Courts, or the legislature, which met at College Green until the Act of Union 1800, and thereafter at Westminster.

Dublin Castle is a major Irish government complex, conference centre, and tourist attraction. It is located off Dame Street in central Dublin.