Driven by a six-blade mahogany fan (see top picture) with a diameter of 9.1m, the tunnel was used to test full-sized aircraft prototypes like the Spitfire.

BBC: NEWS | UK | Magazine | Concrete steeped in history

He and his group realized they could grow silicon wires--chains of silicon crystals 2 to 20 nanometers in diameter and typically 10 microns long--on top of nanosize flakes of gold.

FORBES: Innovators

Early estimates put it at 20ft (6m) deep and 30ft in diameter but officials have created a 100ft-wide safety zone fearing the top of the sinkhole is growing.

BBC: Florida sinkhole: Search for Jeffrey Bush called off