From the BBC: Medieval canals spotted from air.

Archaeologists have found what they have described as a "breathtaking engineering project" in Lincolnshire.

Almost 60 miles of medieval canals, possibly built by monks to ferry stone, have been identified in the Fens.

Although the canals were up to 40ft wide they have filled up with silt and are now only visible from the air.

Experts said the network of waterways represented an achievement not matched until the Industrial Revolution 300 years later. [continue]