A first version of a tiled base map of the Roman Empire was created in 2012 by the author, in collaboration with the Pelagios project. A second version was created afterwards and became part of an online historical geographic information system (GIS) called the Digital Atlas of the Roman Empire (DARE) hosted by the Department of Archaeology and Classical History, Lund University, Sweden and available at http://dare.ht.lu.se. The map was inspired by the Barrington Atlas of the Greek and Roman World (Talbert, 2000) and was built upon digitization efforts carried out by the Pleiades and DARMC projects even though it became necessary to return to the original map for additional data in order to produce a functional digital map. DARE aims at a much higher level of accuracy and the integration of digital resources such as satellite imagery, national topographic maps, source texts, other source material and scholarly literature. Since 2012 we have worked to improve the map regarding both its appearance, quality of location, meta data describing properties of the ancient place and links to related digital resources.
The most prominent change is however the addition of 9111 places (and buildings) with a different provenance than the Barrington Atlas of the Greek and Roman World. The Barrington Atlas was limited to the physical size of the printed atlas, limitations that do not apply the same way to a digital map. Most places that have been added appear in national heritage databases which increasingly have become available online the last years, for instance, the UK based heritage databases Pastscape, Canmore and Coflein covering England, Scotland and Wales respectively. Another important change in the new version of the map is the rendering of natural and semi natural areas (forest, grassland etc.) and bathymetry. In comparison with the map created for the Pleiades project, the map created at Lund University contains an additional zoom level, i. e. zoom level 11. The Digital Atlas and its place database is an active project which is updated at least once a month. In 2015, 822 places were added.
The map itself is also used by Pelagios, Pleiades and other projects to provide a more suitable historical context for their mapping applications. Its gazetteer is implemented in the Pelagios project. The base map is Open Data and can be used by anyone under a Creative Commons BY-SA licence. The projection of the map is Spherical Mercator (EPSG:3857) compatible with most Web mapping software and easy to implement. The maximum zoom level 11 corresponds to a scale at 1:250 000.
In DARE, ancient sites are organized as places and buildings (subsites), each with a distinct place type and location. The buildings are not rendered on the base map because of their close proximity to the places they belong to, but are instead available as thematic overlays (e.g. amphitheaters, theaters, temples etc. respectively). Meta data about places and buildings are available next to the map.
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