Kilmainham Gaol is a former prison

Prison

A prison is a place in which people are physically confined and, usually, deprived of a range of personal freedoms. Imprisonment or incarceration is a legal penalty that may be imposed by the state for the commission of a crime...

, located in Kilmainham

Kilmainham

Kilmainham is a suburb of Dublin south of the River Liffey and west of the city centre, in the Dublin 8 postal district.-History:In the Viking era, the monastery was home to the first Norse base in Ireland....

 in Dublin, which is now a museum. It has been run since the mid-1980s by the Office of Public Works (O.P.W.), an Irish Government

Irish Government

The Government of Ireland is the cabinet that exercises executive authority in Ireland.-Members of the Government:Membership of the Government is regulated fundamentally by the Constitution of Ireland. The Government is headed by a prime minister called the Taoiseach...

 agency. Kilmainham Gaol played an important part in Irish history

History of Ireland

The first known settlement in Ireland began around 8000 BC, when hunter-gatherers arrived from continental Europe, probably via a land bridge. Few archaeological traces remain of this group, but their descendants and later Neolithic arrivals, particularly from the Iberian Peninsula, were...

, as many leaders of Irish rebellions were imprisoned and some executed in the prison by the British and latterly in 1923 by the Irish Free State.
When it was first built in 1796, Kilmainham Gaol was called the 'New Gaol' to distinguish it from the old gaol it was intended to replace - a noisome dungeon, just a few hundred yards from the present site.