A member of the German wireless police picks up signals on the radio equipment he carries on his back, while his colleague takes notes. (Photo by General Photographic Agency/Getty Images). Circa 1925

A workman takes a siesta on a girder during the building of Radio City, the city of New York spread out below. (Photo by General Photographic Agency/Getty Images). Circa 1933

A view of a vintage Rolls Royce limousine with a female driver. (Photo by General Photographic Agency/Getty Images). Circa 1935

Artist Sergio Albiac has launched an experiment in generative portraiture that uses images taken by the Hubble Space Telescope to build up images of people

Last weekend, the National Building Museum in Washington, D.C., opened a 10,000 square-foot ball pit to the general public, and everyone cheered that, finally, someone made their childhood dreams come true.

Engineer Mikhail Venin works on an antenna for the Express AM8 new generation geostationary telecommunications heavy satellite at the large-sized transformed mechanical systems centre of the Reshetnev Information Satellite Systems company in the Siberian town of Zheleznogorsk April 2, 2014. The Express AM6 is a new generation satellite providing services including Russian governmental and presidential mobile communication, digital television and broadcasting, according to the Reshetnev company representatives. (Photo by Ilya Naymushin/Reuters)

Having $100 in your pocket would be so much cooler if it was designed by Martin Joubert. He went all out and created a number of different designs for the 100 USD banknotes, ranging from silly to witty. We especially liked the one with “That’s right. This is real money” written on it, showing just how many cups of coffee, basketballs, and guns you can buy with 100 dollars. All in all, even the currency that we have today is nothing but paper, even though it looks official and strict. There is nothing backing it up except for our noble military that ensures that Gulf States sell their oil using only the “green” kind of currency. (Photo by Martin Joubert)

Wedges of an orange generate enough current and electrical juice – 3.5 volts – to power an LED. The fruit’s citric acid helps electrons flow from galvanized nails to copper wire in this 14-hour exposure. This image was published in September’s Visions of Earth, a trio of photos that appear in each issue of National Geographic. (Photo by Caleb Charland/National Geographic)