A photograph of two Zeppelins in a hangar. Referred to as "German dreadnoughts of the Air" a Zeppelin is a type of rigid airship created originally from the concepts of Count Ferdinand von Zeppelin in the early 20th century. First flown commercially in 1910, and used extensively as bombers in the First World War by the Germans. Experienced popularity as a method of flight in the 1930's, but the 1937 Hindenburg disaster, as well as political/economic issues, began the downturn in use of Zeppelins. (Photo by: Universal History Archive/UIG via Getty Images)