In preparation of the first paleoseismic trenching in the NE border of the Roer graben (the Netherlands), site selection was carried out. Combining geological and seismological information and using existing aerial photographs, seismic reflection and geodetic levelling data, it was decided to focus on the Peel boundary fault near the village of Neer. Detailed information on the exact location of the fault was obtained through geophysical techniques, mainly ground penetrating radar (GPR) and resistivity measurements. GPR data unambiguously showed the flexuring and offset of reflectors affected by the fault. Performing eleven GPR profiles along strike allowed to obtain a 3D picture of the fault, laterally extending the information given in the trench.