The heritage data being made available by National Monuments Service is undergoing continuous revision and update. It is recommended that users refresh downloads at regular intervals.
Data quality
The base mapping and imagery on the Historic Environment Viewer utilises the Ordnance Survey Ireland (OSI) MapGenie web-services and the displayed mapping is at 1:5000 and greater scale. It is important to note that this mapping uses the Irish Transverse Mercator (ITM) co-ordinate system. In order to facilitate users during the transition from Irish Grid (IG) to ITM, downloads will include both sets of co-ordinates. Please note that the centre point of each record displayed on the site is not indicative of the geographic extent of the monument. The existing point centroids were digitised relative to the OSI 6-inch mapping and the move from this older IG-referenced series to the larger-scale ITM mapping will necessitate revisions. The accuracy of the derived ITM co-ordinates is limited to the OS 6-inch scale and errors may ensue should the user apply the co-ordinates to larger scale maps.
Records that do not refer to 'monuments' are designated 'Redundant record' and are retained in the archive as they may relate to features that were once considered to be monuments but which on investigation proved otherwise. Redundant records may also refer to duplicate records or errors in the data structure of the Archaeological Survey of Ireland.
GIS Web Services and Open data downloads
For users with access to GIS software please note that National Monuments Service data is available as spatial data web services and bulk data downloads via the government Open Data Portal.