The Czar's cannon, a 40 ton machine, was mostly, they say, created to spook the enemy. No one knows for sure, but it was probably fired once (a 1980 study found traces of gunpowder). It was build in the 16th century of 100% brass and is over 17 feet long. The cannon could not actually shoot the one ton balls sitting in front. They were also created to spook the enemy. The cannon probably shot a load of smaller balls. Compared to cannons I've seen in the U.S. and other countries, it is elaborately decorated, including an elaborate equestrian carving of a Czar. Our guide said that Napoleon Bonaparte considered taking the cannon back to France as swag after the French invasion of Russia.