GPR is establishing as a new technique in Archaeological Prospection. It is based on electro-magnetic waves propagating in the subsurface dependent on frequency, conductivity and the dielectric properties of the material. At discontinuities, where these properties are changing, they are partially reflected. Therefore GPR is best for locating subsurface stonewalls. The main components of a radar device are two antennas: one to transmit the electromagnetic wave into the ground, the other to record the reflected signal dependent on the twice-way-travel-time. A typical point-density is 10x50cm. To get a high-quality picture of the ground-structures, it is necessary to process the data with proceedings of the reflection-seismic measurements (e.g. band-pass filter, gain, static corrections and migration). By creating a 3D-picture, it is possible to generate time or depth slices of 5-10cm thickness to show the exact depth structure of an archaeological object.