Lesser-Known Weapons of World War II
Believe it or not, the massive machine in the picture above was actually a cannon, the Vergeltungswaffe 3, designed by the Nazis. The super gun was built directly into a hill and designed to shoot artillery shells across the English Channel, blasting from France directly into London. While it was able to fire shells up to 58 miles, the whole thing was a failure—which is precisely why you've probably never heard of the Vergeltungswaffe 3.
If you think that's interesting, you won't want to miss io9's great roundup of 11 impressive-looking weapons from WWII that most people never knew existed—such as explosive dead rats and 11,000 pound jumbo tanks.