The National Monuments Service hosts this excellent website. It includes a monuments database with map links to all of the registered monuments in the Republic of Ireland.
  Bodleian Library Map Room
The Map Room has an extensive range of books on cartography and GIS. A large selection of atlases are available, together with journals, gazetteers and other reference works.
  An Brainse Logainmneacha/Placenames Branch
Déanann an Brainse Logainmneacha taighde ar logainmneacha na hÉireann. Soláthraíonn an Brainse foirmeacha oifigiúla Gaeilge de logainmneacha d'eagrais phoiblí nuair a iarrtar iad. Government department responsible for researching Irish placenames and providing Irish placename forms to public bodies on request.
  British Library map collections
Search or browse the British Library map catalogue.
  Bunachar Logainmneacha na hÉireann/Placenames database of Ireland
Searchable site run from DCU.
  Griffiths Valuation maps
The online database has accompanying OS maps showing individual plots in each townland.
  Harvard Map Collection
Search Harvard's print and digitial map collections.
  National Monments Service
Includes interactive maps, which zoom up to aerial photograph level. A searchable database lists every national monument in the country.
  Placenames NI - The Northern Ireland Place-Name Project
Online database, with searchable maps and index, giving the history of the 9,600 townland names of Northern Ireland.
Ordnance Survey of Ireland Historical Mapping Archive
The first editition OS 6-inch maps of all parts of Ireland are now available online. Subscription service. There is also a free map viewer on the OSi site, searchable by county, townland name etc.
The Pointer site includes a townland name search facility with accompanying maps and a history of each townland name in Northern Ireland, run by the Northern Ireland Place-name Project.
  Scottish Place-Name Society
The Society, launched in February 1996, exists for the support of all aspects of toponymic studies in Scotland, and in particular the work of the Scottish Place-Name Database at the  University of St. Andrews and the University of Edinburgh.
Townlands of County Monaghan
Monaghan County Council's website gives free access to 1:50,000 OS maps and aerial photographs for the county, searchable by townland name.
  Townland Database
Searchable database listing townlands in every county, giving acreage, barony, civil parish and PLU.
  UK National Archives, early Irish maps
Early Irish maps from State Papers c.1558 - c.1610, available online at affordable cost.
Ulster Place-name Society
The Society is surveying place-names in Ulster and publishes both a journal, Ainm, and stand-alone books giving the results of the areas they have surveyed.
  Taylor and Skinner Road Map of Ireland 1778
Colour maps, free website.

"This project has been funded by Cavan-Monaghan Rural Development Co-op under the National Rural Development Programme. Funded by the Irish Government and part-financed by the European Union under the National Development Plan 2000-2006."