from a standing start the USAAF Eighth Airforce (only a part of the USAAF establishment in Britain) built 132 airfields, 9,700,000 sq feet of warehousing and depots, housing for over 500,000 personnel (more than Washington DC at the time), moved 16,400,000 cubic yards of soil, laid 46,000,000 square yards of concrete and 262,000,000 bricks.
Interestingly none of the airfields had a security perimeter of any sort. Such was the mood of the population it wasn’t felt necessary. Imagine that today, anything not nailed down would be nicked.
Courtesy of ‘Big Week’ by James Holland, an excellent read.