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About this project

The British Library’s Georeferencer project is crowdsourcing location data to make a selection of its vast collections of maps fully searchable and viewable using popular online geotechnologies.

Online geographic tools allow historic maps to be overlaid on modern mapping, enhancing the ability to view and compare the past with the present and improving findability. Georeferencing, i.e. assigning points on a map image to corresponding geographical coordinates, links the map to its spatial location on the ground using universal geographic standards (latitude / longitude).


The British Library began a project to crowdsource the georeferencing of its scanned historic mapping in 2011 by partnering with Klokan Technologies to customise its online georeferencing tool. There have been five public releases of maps since 2012, all of which met with tremendous success. In total over 8,000 maps have been "placed" by participants and subsequently checked for accuracy and approved.

The maps

The most recent release, of July 2014, consisted of 3,220 maps that can be described simply as “Maps within 19th-century Books”. These are among the illustrations extracted from books digitised by Microsoft. The images were posted to Flickr Commons in December 2013, and were then tagged by the public, including identifying those that were maps. This collection therefore represents a great deal of public interaction!

Previous to that, the Library’s collection of British and Irish first-edition Chas E Goad Co. fire insurance plans, were posted online, and georeferencing was completed in January 2014. These 2,500 maps cover 53 towns, cities and ports, and provide detailed information about buildings, land use and urban design at the at the turn of the twentieth century (1886-1930). Over. Two smaller map collections were also included, one related to Britain and the American Civil War, and the other a selection of WWI maps.

Releases in 2012-2013 included a variety of maps dating from as early as the 16th century up to the twentieth century. Initially, two well-known British collections were released The Ordnance Surveyors’ Drawings and the Crace Collection of maps of London, followed by materials from King George III’s Topographical Collection and maps contained within 16th and 17th century manuscripts. The variety of materials then expanded even further, reflecting a wider date range and geographic coverage. Maps of a modern vintage represented the themes of car, rail and air transport, along with topographic and military mapping. This has resulted in a better-rounded, if less orderly, representation of mapping of the UK and other regions of the world.


Through georeferencing, the selected map images were spatially enabled, making them geographically searchable and able to be visualised using geospatial tools and combined with other maps online. All georeferenced maps are added to the portal Old Maps Online, which uses a geographic search interface to identify and view historic maps from numerous collections online.
The output of this work may also be viewed using the BL Georeferencer interactive map and directly from the Online Gallery map pages.
The Library is grateful to all the participants who generously contributed their time. Special thanks are extended to the expert panel of Reviewers, whose work to ensure the high quality of results was substantial. The appointed BL Georeferencer Reviewers are:
Chris Austin
Susan Major
Maurice Nicholson
Mark Setrem
Ian Pritchard
Kathryn Snow

Further information

Any queries about this project should be directed to To connect with other users of this technology and participate in discussions, join the User Group of our technology supplier, Klokan Technologies, at
For more information on the initial implementation of the British Library Georeferencer, see

  • KC Kowal and P Pridal. “Online georeferencing for libraries: the British Library implementation of Georeferencer for spatial metadata enhancement and public engagement” Journal of Map & Geography Libraries: Advances in Geospatial Information, Collections & Archives, 8:3, 276-289. Online access.

For information about georeferencing in libraries in general, see

  • C Fleet, K. Kowal and P. Pridal “Georeferencer: crowdsourced georeferencing for map library collections”. D-Lib Magazine 18(11/12): 2012. doi:10.1045/november2012-fleet Online access.