The earliest surviving complete census of all of Ireland is now available at the click of a mouse.
More than 4.5 million records made by 850,000 households on census night in 1901 have been put online for the public to access.
The census provides personal details including religion, profession, and if the person spoke Irish or English.
It was launched on Thursday by the Republic's Minister for Tourism, Culture and Sport Mary Hanafin.
Famous historical and literary figures can be easily traced.
The census lists James Joyce as a 19-year-old student living with his family in Fairview, Dublin.
Fires and pulpage
It also details the two-year-old C.S. Lewis, then living at Dundella Avenue in Victoria, Down, with his parents, brother and two servants.
At 17, author John Ervine, recorded his profession as a clerk, and lived in Lisbon Street in Pottinger, County Down, with his mother, sister and four boarders.
Also listed is Thomas Andrews the shipbuilder in charge of the plans for the Titanic, who died on its maiden voyage.
He was then an "assistant shippered manager", boarding with a family at Wellington Place in Belfast.
Digitisation of the records cost almost 4m euros and was carried out by the National Archives in partnership with Library and Archives Canada over the past five years.
There are now no further complete sets of records to make available.
The 1911 Census records went online in 2009 and have recieved more than 260m hits.
Most of the census records from the 19th century have been lost for a variety of reasons including a fire at the Public Records Office during the Civil War in 1922, and records being pulped because of a paper shortage during First World War.