Bonbibi, Treehouse Point, Fall City, WA. The Bonbibi is balanced on two steel yokes. The yokes spread out the load and allow for tree growth and movement in the wind. A small deck hangs from the beams below and uses the treehouse itself to shelter guests. (Photo by Pete Nelson)

Tsar Alexander II (1818–1881) known as “The Liberator” lying in state. He was mortally wounded by an assassination attack in St Petersburg. (Photo by Hulton Archive/Getty Images). March 1881

Two guards perform an execution in China, one holding the gun, the other holding a mask over the victim's face. (Photo by General Photographic Agency/Getty Images). Circa 1925

The first load of passengers queuing for the Bennie Railplane in Glasgow; the inventor George Bennie is third in the queue. The streamlined cars are self propelled, driven by air screws in front and behind, and hang from a steel girder. (Photo by J. A. Hampton/Topical Press Agency/Getty Images). 4th July 1930

The Slauerhoffbrug (English: Slauerhoff Bridge) is a fully automatic bascule bridge (aka tail bridge) in the city of Leeuwarden in the Netherlands. It uses two arms to swing a section of road in and out of place within the road itself. It is also known as the “Slauerhoffbrug ‘Flying’ Drawbridge”. A tail bridge can quickly and efficiently be raised and lowered from one pylon (instead of hinges). This quickly allows water traffic to pass while only briefly stalling road traffic. The deck is 15 m by 15 m. It is painted in yellow and blue, representative of Leeuwarden's flag and seal.

Guests on the terrace of Shepheard's Hotel, Cairo, circa 1940. (Photo by Hulton Archive/Getty Images)