The Great Cannon is a siege unit that cannot be created during normal gameplay. It is found in the campaign "Act II: Ice" of Age of Empires III, wherein it is very strong heavy Russian artillery. In the level, players must halt and destroy Great Cannons in order to prevent them from crossing the player's starting position. The Great Cannon is pulled by two cavalry (like the Great Bombard) and has the firing sound of a ship gun. It is very effective against infantry and can only be countered effectively by cavalry in hand-to-hand combat and anti-artillery artillery.
Redoubt cannon is a large cannon looking similar to the great cannon, which cannot move, making it more of a Defensive Structure.
"Cannon are large guns capable of firing over considerable distances. The largest cannon are typically called "bombards."
One famous Russian cannon is known as the Tsar Cannon. It is a huge cannon weighing 40 tons and was meant to defend the Kremlin in the event of a war. The Tsar Cannon was made in 1586 and a carriage was made to carry it in 1835. According to the Guinness Book of World Records, the Tsar Cannon is the largest howitzer ever made."