In the well-known Roman town Carnuntum in the eastern part of Austria, systematic geophysical prospection has started recently. A five hectare area of the civil town, the former residence of Emperor Marcus Aurelius, was prospected by resistivity and magnetic surveys in 1996. Resistivity and magnetic surveys are arithmetically combined or colour coded in a digital image processing technique for a combined archaeological interpretation using geographical information systems' procedures. Image combination facilitates correlation of the two data sets and offers new insights for the interpretation process. The results of the first survey show the layout of the town, i.e. roads and insulae. A part of the Roman town at the River Danube is now recovered, unveiling a lot of archaeological information about the hitherto unexplored archaeological area. A representative building and a square have been identified that might represent the town’s forum, with the building probably representing the curia.