The project is described in this article. The digital map has been created by Johan Åhlfeldt with support from the Pelagios project.

License

The transmission of the tiles to any web-mapping application is permitted under a Create-Commons 3.0 (CC-BY) licence. Attribution to the Pelagios project is required and linking to this About page is encouraged.

Legend: Names, symbols and order of appearance

PlacenameZoom
Ancient placename (major places) e.g. Herculaneum7
Ancient placename (all other places) e.g. Stabiae9
Ancient rivername e.g. Aufidus (repeated)6
Ancient lakename e.g. Lemannus7
Modern placename e.g. Terzigno9

SymbolDescriptionZoom
Major settlement (capital, colonia, municipium)6
Major fort (legionary fortress)6
Major sanctuary or temple7
Settlement (civitas, vicus, other settlement)8
Fort (castrum, castellum)8
Road or coastal station8
Oasis9
Sanctuary or temple9
Bath9
Tumulus10
Cemetery10
Monastery or church10
Villa10
Mine, quarry or production10
Pass10
Bridge10
   
 
Province, e.g. Raetia5-7
 
Major road5
 
Minor road7
 
Aqueduct7
 
Limes, citywall7
 
Perennial/Permanent lakes and rivers5
 
Non-Perennial/Intermittent/Fluctuating lakes and rivers8
Elevation  
 
5000 m 
 
4000 m 
 
3500 m 
 
3000 m 
 
2500 m 
 
2000 m 
 
1500 m 
 
1000 m 
 
500 m 
 
0 m 
 
Sea level (Coast lines are modern) 
 
Below sea level 

The making of the map

The software Mapnik 2.0 for Windows, has been used to create the map tiles. It creates tiles at 256x256 pixels projected in Sherical Mercator Projection (EPSG:3857) and organizes them in a directory structure according to zoom, x and y position. Mapnik takes as input various data sources. From the Shuttle Radar Topography Mission (SRTM) dataset, elevation at 90m resolution, raster data (in geotiff format) like hillshade, color-relief and elevation contour lines (shapefile) have been created using the Geospatial Data Abstraction Library (GDAL) commandline utilities. They all depict the topography of the Roman Empire. On top of that, modern coastline, rivers and lakes (in shapefile format) have been added. The Pleiades dataset was improved, extended with new content compiled manually from the Barrington Atlas and imported to a PostGIS SQL database, used by Mapnik as input source.

Sources

The point of departure for this project has been the Pleiades dataset, which is a digitization of the Barrington Atlas and the accompanying map by map directory, carried out by Pleiades and the Digital Atlas of Roman and Medieval Civilization (DARMC) project at Harvard. The dataset is available in different formats at the Pleiades website and licenced under Creative Commons CC-BY 3.0. The feature data and coordinates have been improved to make it possible to sucessfully render the digital map, with special focus on the 1478 places considered as most important by the Barrington Atlas. Data about ancient name and importance of place has been derrived from careful and repeated study of the original atlas; that is, I manually checked the Atlas and its maps several times for the occurence of important places depicted with capital letters, and modern names depicted with a sans-serif font.

The Roman roads network, also digitized from the Barrington Atlas, is courtesy of the DARMC project, Harvard university. Another important source of geodata is the Antiquity à la carte online GIS application, with downloadable data of aqueducts, ancient coastlines and roads. Most of the map symbols have been derived from this website. All content from Antiquity à la carte is CC BY-NC 3.0.

It has been our aim to georeference places on the map as precisely as possible using modern cartographic and georeferencing tools (Google Earth/Maps, Bing satellite imagery, Google geocoder service, maps from national geographic agencies). At best, it is possible to gain an accuracy of a few meters where lucky circumstances make it possible to spot individual sites on satellite imagery for verification, around 1000 sites. Identifying and labelling locations accurately has become quite a big topic in several online communities and through efforts by individuals - Wikipedia, Pleiades, Megalithic Portal, OpenStreetMap, History Illustrated group (Google Earth Community), Livius.org: articles on ancient history, Viae Romanae, Histolia - Die türkische Südküste in der Antike, Ancient Near East on Google Earth (ANE), Vias Romanas em Portugal - to name but the most important ones for this work. For everyone with an interest in North Africa, and for a degree of detail greater than most online maps, the North Africa AMS Topographic Maps are available as scans from the PCL Map Collection, University of Texas libraries.

Johan Åhlfeldt