The primordial advantage of aerial surveillance comes from the fact that the scale of the photos is known. We can thus measure these structures, know the module that was employed, and eliminate everything that is standardized according to recent norms. Thus, when we run across the metric system being used, it is clear that these "pseudo-centuriations" actually date from after the French Revolution!

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Protohistoric circles and bomb craters (bombing of a German V1 rocket military base in 1944).

Zigzagging military trenches from 1918, in the vicinity of a protohistoric circle and Henry IV's siege line built for the siege of Amiens.

An enigmatic site — perhaps an ancient grove turned into a hunting lodge or pleasure pavilion.

The lime markings on this abandoned soccer field still retain moisture.

Mushroom circles are smaller and more irregular than protohistoric circles.

There is nothing archaeological at all about these circles — they are the result of rotating watering devices used in pastures!