Students pose for a pictures taken by their friends during spring break on the beach in the resort city of Cancun, Mexico, February 27, 2009. (Photo by Israel Leal/AP Photo)

A tour group wanders through block 7 of Eastern State Penitentiary in Philadelphia, Pennsylvania April 30, 2014. Opened in 1829, with the original corrective system of “confinement in solitude with labor”, the penitentiary housed about 75,000 inmates in its 142 years of operation. At Eastern State reunions, former inmates, staff and guard gather to share memories and trade stories and get a chance to describe their experiences in question-and-answer sessions with the public. (Photo by Mark Makela/Reuters)

Participants try to cover themselves from color powder sprayed by volunteers as they run through a “color station” during a five-kilometer color run event held in Beijing, China Saturday, June 21, 2014. (Photo by Andy Wong/AP Photo)

Two men standing on a high catwalk, surveying the construction of the Brooklyn Bridge, with Manhattan in the background, New York City, 1877. (Photo by Museum of the City of New York/Archive Photos/Getty Images)

Sally Fitzgibbons of Australia competes in the Women's Final of the 2012 Australian Surfing Open on February 19, 2012 in Manly, Australia. (Photo by Cameron Spencer/Getty Images)

Color dyed rabbits are seen in the markets of the Souq Waqif on January 12, 2011 in Doha, Qatar. (Photo by Robert Cianflone/Getty Images)

Adolf Hitler, Alfred Rosenberg (left) and Dr. Friedrich Weber of the Freikorps Oberland (Oberland Free Corps), during the Munich Putsch. (Photo by Keystone/Getty Images). 1923