Magnetometry is nowadays the most efficient non-destructive geophysical method of modern archaeology. This technique puts emphasis on the measurement of anomalies of the Earth’s magnetic field, caused by the presence of archaeological remains in the ground. Total field caesium magnetometer with a sensitivity of +/-10 pT has proven to give the best results in terms of a high speed and high resolution prospecting of large areas. Data collected in a 25 x 50 cm raster are typically converted into a 256 greyscale values, digitally transformed and filtered by the use of highly developed image processing software. The magnetograms are the base for further detailed geophysical and archaeological interpretation of sites.