A non-invasive method of buried-utility-mapping includes using a long wavelength gradiometric ground penetrating radar to “see” patches of conductive material below ground and buried pipes and electrical conductors that are all constantly radio-illuminated by local AM radio broadcasts. The underground infrastructure of entire cities can be surveyed this way, point-by-point over time. A short wavelength part of the gradiometric ground penetrating radar operates shoulder-to-shoulder with the magnetic part and is able to improve shallow object resolution, map moisture build-ups under roads, and spot contaminated soils. Two gradiometric ground penetrating radar technologies, cameras, and navigation receivers can be mounted on city vehicles and a daily collection of their data batch transformed by digital processing algorithms into detailed and automatically updating false-color maps of the underground utilities of the whole city and other buried infrastructures.