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Ordnance Survey Maps

  • The first edition Ordnance Survey maps, surveyed in the 1830s and 1840s, cover all counties of Ireland. The scale is six inches to one mile, and the maps are available digitally and on microfiche.
    • Digital copies may be viewed using the Ordnance Survey of Ireland Historic Map Viewer.  Please note, however, that it is necessary to pay to print copies from this resource.
    • It is also possible to view digital copies of these maps for some individual counties on the Web. Maps for counties Clare, Donegal, Galway, Mayo and Sligo may be accessed at the public library websites of those counties.  Links to these sites may be found at the Public Libraries index. Please note that at present it is necessary to download an Adobe SVG plug in [available free from Adobe] to view the maps on these sites.
  • The microfiche copies of these six-inch maps are located in the Special Collections Microfilm Room in the Hardiman Building and they may be viewed and copies downloaded on the microform readers.
  • Revised editions of the six-inch maps were produced in the later 19th and early 20th centuries. The Library holds these maps in hardcopy for County Galway only, located in Cabinets E and F in the map area. In the 1890s, a larger scale (25 inches to one mile) was produced.  Digital editions of this series, for all of Ireland, are available on the OSI Historic Map Viewer.
  • Ordnance Survey maps of the city of Galway, with the very large scale of ten feet to one mile and dated 1872, are located in Cabinet D in the map area. There are 49 maps as well as an index map indicating the areas covered.
  • A series of maps was produced in the 20th century, with the scale half-inch to one mile. The Library holds this series for all of Ireland. They are located in Cabinet R under the stairs.  Please ask staff at the Customer Services Desk for help with consulting these.
  • The latest Ordnance Survey of Ireland, with a metric scale of 1:50,000, is known as the Discovery Series. A parallel set, known as the Discoverer Series, covers northern counties on both sides of the border. The Library has a full set of these maps in paper format, and they are located in Cabinets A and B in the map area.

Related material

  • The original manuscript versions of O’Donovan’s Letterbooks were produced during the survey for the first edition OS maps in the 1830s and 1840s. The books for some counties were later produced in typescript format. These Letterbooks give descriptions of historical and archaeological sites and also contain some drawings of notable antiquities.  The available typescript volumes are held in the Special Collections Reading Room. Four Masters Press in Dublin is engaged in a project to produce all of the volumes in book format. To date counties Donegal, Down, Dublin, Galway, Kildare, Kilkenny, King’s (Offaly), Laois, Mayo and Meath have been published.  Data from Letters for County Clare is available online at Clare Library website.
  • The Ordnance Survey Namebooks were also produced at this time.  These are more comprehensive than the Letterbooks as they cover every townland in each county.  Physical descriptions of the townlands, including antiquities, are noted and explanations of the place names are given.  About 16 counties were later produced in typescript form and these volumes are held in the Special Collections Room, with the remainder on microfilm at 941.5ODO. The data for county Galway is available on Galway Library website. Name Book entries for some other Irish counties are being made available on the Askaboutireland website under the Griffith’s Valuation search resource.

A detailed guide to using our Map Collections is available in print, or download Map Resources in the Library and Online.



Marie Boran

Boran, Marie

Special Collections Librarian
Tel: +353 91492543

Margo Donohue

Donohue, Margo

Research and Learning / Acquisitions Assistant
Tel: +353 91 493476

Geraldine Curtin

Curtin, Geraldine

Research and Learning Assistant
Tel: +353 91493476