Non-invasive high-resolution geophysical techniques, such as ground penetrating radar (GPR), electrical tomography and seismics, have been applied in archaeological investigations during a geophysical survey, which took place in the archaeological site of Itanos in Greece. The main objective of survey was to delineate the remains of buried relics in selected areas by combining these high-resolution geophysical methods. Three sets of GPR antennas were employed to achieve optimal system performance. GPR time slices, presented in a series of maps and electrical tomography resistivity sections revealed features at different depths related to soil resistance and magnetic gradient anomalies, attributed to buried relics of building walls. In particular, in the ancient harbor compatible results were obtained from seismic refraction, surface waves, GPR, electrical tomography and other geophysical methods, indicating that the depth to the bedrock is varying from 2 to 10 m.