National Archives of Ireland

Researching your Irish Ancestry can be notoriously difficult, but the National Archives of Ireland holds a wealth of information, searchable on-line.
Unfortunately almost all the records acquired by the Public Record Office of Ireland before 1922 were destroyed by fire and explosion at the beginning of the Civil War in June 1922 and as a result, the material now held by the National Archives dates mainly from the 19th and 20th centuries, although there are a few surviving court and exchequer rolls dating to the early 14th century.
However they are still well worth visiting, as they also provide excellent guides to searching the archives and researching Irish family history
Some of the most frequently consulted archives:
Archives acquired from private sources
Census 1901
Census 1911
Chancery pleadings
Chief Secretary's Office Registered Papers
Church of Ireland parish registers
Convict Reference Files
Coroners' inquests
Dáil Éireann records
Departmental records
Famine Relief Commission records relating to the Famine
Ferguson manuscripts
Genealogical abstracts (Betham, Crosslé, Tenison Groves, Grove-White and Thrift)
General Prisons Board
Incumbered and Landed Estates Court rentals
Irish Record Commission calendars
Lodge's manuscripts
National School applications, registers and files (pre-1922)
Office of Public Works
Official Papers
Ordnance Survey
Outrage Reports
Probate records
Quit Rent Office
Rebellion Papers
Society of Friends Famine Papers
State of the Country Papers
Trade Union archives
Valuation Office and Boundary Survey records
Will books and grant books