Their Website includes an entirely interactive map of the country, with historic layers. Between 1829 and 1842 the Ordnance Survey completed the first ever large-scale survey of an entire country. Through the Website you can view and download this data or place an order for delivery by mail.
The new archive currently comprises the following series of maps:
The above historic maps, originally surveyed on a county basis, now make up Ordnance Survey Ireland's digital image archive. Every image in the archive has been captured from an original print and each digital map image is now a seamless map title within the archive.
The site also contains the Lewis Topographical Dictionary. As the site notes, "Samuel Lewis first published his two volumes of The Topographical Dictionary of Ireland in 1837. His main aim, along with his previous topographical dictionaries and maps of the United Kingdom, was to give in ‘a condensed form’, a reliable and unbiased description of each place. Arranged alphabetically by place (village, parish, town, etc.), it provides a comprehensive description of all Irish localities as they existed at the time of publication. Lewis gives details about every parish, town and village in Ireland, including numbers of inhabitants, the economy, history, topography, religion and parish structures, administration and courts, schools, and much more. He also gives the names of the principal inhabitants (generally landlords, merchants and professionals). Lewis's dictionary is the first detailed study of its kind for Ireland, and since it was published just prior to the Irish Potato Famine (1845-49) it is a valuable resource used widely by historians and genealogists alike."