2 A Roman city uncovered
A portion from the large-scale flux-gate gradiometer survey conducted over the Roman city of Wroxeter in the UK. Under ideal conditions such as these, the magnetometer can reveal a wealth of archaeological detail, including the Roman street plan (the rectangular lattice shown clearly at the top) and even the outline of individual buildings. The black and white diagonal lines running from the top left to the bottom right of the image are modern water and gas pipelines. The white regions were not surveyed.