Members of the American Civil War Society take part in a mock battle in the grounds of Cusworth Hall, South Yorkshire on July 2, 2011 in Doncaster, United Kingdom. Enthusiasts from all walks of life are taking part in re-enacting scenes from the American Civil War and in 'living history' events which are as authentic as possible. (Photo by Christopher Furlong/Getty Images)

Airmen and their Japanese dates “do” the town together, visiting the local points of interest. Almost every community in Japan has it's famous shrines and parks. Tachikawa boasts beautiful environment. Girls are wearing western dress, May 1952. (Photo by National Archives and Records Administration)

Stunning silhouettes under European cities reveal the size and splendor of the continent’s urban foundations. Photographer and content-manager Anna Arinova, 28, from Moscow, captured the awe-inspiring labyrinths in Russia and Germany. Here: Regenwurmlager, Poland. The Regenwurmlager is an extensive underground fortification area constructed by Germany in 1920s-1940s, now in western Poland, near the city of Międzyrzecz. (Photo by Anna Arinova/Caters News)

A ship builder walks past a section of the Oasis Class 3 cruise ship at the STX Les Chantiers de l'Atlantique shipyard site in Saint-Nazaire, western France, February 17, 2015. The Oasis-class III vessel is scheduled for delivery in mid-2016. (Photo by Stephane Mahe/Reuters)

The Porsche 919 Hybrid No17 of the Porsche Team driven by Timo Bernhard of Germany is seen in action during the 83rd 24-hour Le Mans endurance race, in Le Mans, western France, Saturday, June 13, 2015. (AP Photo/David Vincent)

Lake Assal is a crater lake in central-western Djibouti. It is located at the western end of Gulf of Tadjoura in the Tadjoura Region, touching Dikhil Region, at the top of the Great Rift Valley, some 120 km (75 mi) west of Djibouti city. Lake Assal is a saline lake which lies 155 m (509 ft) below sea level in the Afar Triangle, making it the lowest point on land in Africa and the third-lowest land depression on Earth after the Dead Sea and Sea of Galilee.