Colonia Ulpia Traiana is the only Roman city north of the Alps whose remains have remained extensively accessible for research. To date, however, less than one-fifth of the ancient city has been excavated. Modern methods should make it possible to look into the ground more quickly.
Relaxing on historic ground … just a few centimetres over Roman layers. Geophysical prospectors cover the ground on foot.
One of the dilemmas faced by archaeologists is that their excavations frequently also mean destroying the excavated layers. The objective on the APX site is therefore not to expose as large an area as possible. Instead, the excavators in Xanten concentrate on areas in which intervention in the ground is unavoidable, as well as on areas which promise to yield specific information on the Roman city.
In optimum cases, concealed structures in the ground become clearly visible.
Ground radar, measurement of electrical resistance and geomagnetics permit a first non-destructive look into the ground. Different densities and electrical conductivity of the subsoil are measured down to a depth of more than two metres. Not uncommonly, this reveals the remains of walls, as well as layers of loose rubble and other anomalies. The results are charted in maps providing a first indication of the structure below the turf.
The APX has teamed up with the Berlin-based eastern atlas company in a research project which aims to survey the entire area of the Roman city using non-destructive geophysical methods. The measurements have already yielded exciting insights into the nature of the ancient city. However, they can never provide the same insights into Roman life as excavations.