The magnetic prospection is the most widespread geophysical method for archaeological investigation. Using multi-sensor arrays of fluxgate gradiometers large areas can be surveyed in short time. Diverse types of objects and structures are detectable: pits, ditches, walls and foundations, fireplaces, ovens and furnaces. The contrast of the magnetic susceptibility of the searched material in relation to the surrounding soil or rock is decisive for the detectability. Flexible instrumentation allows the use of magnetic prospection in open and flat regions as well as in hilly and mountainous areas. The arrays can be equipped with 4 to 10 or even more probes and can either be moved on wheels or carried by hand.