By the order of Moscow Region archaeological expedition of the Institute of Archaeology, Russian Academy of Science (RAS), GPR inspection of an ancient settlement excavation (D'yakovsky period, early iron age, 4-3 centuries BC) was carried out. This ancient settlement is located near village Myachikovo in Kolomna district of the Moscow Region. The inspection of the excavation was carried out by the georadar GROT (design of the device has been reported at the 6th GPR Conference in Sendai, Japan). The research problem consisted in the mapping of buried earthen fortification structures of the ancient settlement. According to the data of aerial photography, sectors of two concentric strips, distinguishable due to more saturated color of vegetation, were well visible in the territory surrounding the excavation. According to the archaeologists version, the vegetation indicated the borders of the interred fortification structures. The GPR inspection of the territory around the settlement showed, at the depths of 1.5 to 2 meters, some structures similar to a buried ditch. The 'ditch' width was about 5 - 6 meters; radius from the settlement center was 20 meters for the internal, and 30 meters for the external ditch. Georadar cross sections superimposed on the excavation map allowed us to understand the scheme of ditch arrangement in fortification structures of an early iron century settlement.