In what year did Dublin become the capital of Ireland?

Dublin is the capital and largest city in Ireland. Dublin is in the province of Leinster on the east coast of Ireland, at the mouth of the River Liffey and bordered on the south by the Wicklow Mountains. The population of the Dublin Region, as of 2016, was 1,347,359 and the population of the Greater Dublin area was 1,904,806.

There is archaeological debate regarding precisely where Dublin was established by Celtic-speaking people in the 7th century AD. Later expanded as a Viking settlement, the Kingdom of Dublin became Ireland's principal city following the Norman invasion. The city expanded rapidly from the 17th century and was briefly the second largest city in the British Empire before the Acts of Union in 1800. Following the partition of Ireland in 1922, Dublin became the capital of the Irish Free State, later renamed Ireland.