Two men using an electric power saw to fell a tree circa 1940's. (Photo by Keystone View/FPG/Getty Images)

Nazi dictator Adolf Hitler greets supporters at a May Day gathering in the Olympic Stadium, Berlin. (Photo by Keystone). 1st May 1938

Marianne Brauns jumping a breakwater on the beach, wearing a structured blue swimsuit with white trim. (Photo by Carl Sutton/Hulton Archive/Getty Images). Circa 1950

A rail worker fixing a fog warning notice at South Woodford Railway Station in Essex. (Photo by H. F. Davis/Topical Press Agency/Getty Images). 20th October 1938

A bunker at aformer Swiss artillery fortress called Heldsberg stands near the town of St. Margareten, Switzerland March 22, 2015. Heldsberg fortress, located on the Swiss-Austrian border near the River Rhine and Lake Constance was built from 1938 to 1940 and remained in military use until 1992. Since 1993 it is open to the public as Fortress Museum Heldsberg. (Photo by Arnd Wiegmann/Reuters)

Girls of University of Cincinnati Stage Grecian Games on April 29, 1921. Garbed in costumes of ancient Greece, fair students of the University of Cincinnati, Ohio arranged a set of Grecian Games for the benefit of the University athletic fund. All of the girl students of the University, who take a great interest in outdoor games and athletics, took part in the games. The fund was greatly increased through the staging of the unique attraction and the girls purpose to give a return engagement. The accompanying photographs show the girl contestants in their Grecian costumes. Photo shows the start of the 100 yard dash. (Photo by Bettmann Archive/Getty Images)

“Monorail Subway, Capitol To Senate. The Car. Senators Swanson And Townsend As Passengers, 1916”. (Photo by Harris & Ewing Collection). (Please click to enlarge)