List of the largest cannon by caliber

The list of cannon by caliber contains all types of cannon through the ages listed in decreasing caliber size. For the purpose of this list, the development of large-calibre artillery can be divided into three periods, based on the kind of projectiles used, due to their dissimilar characteristics, and being practically incommensurable in terms of their bore size:
Cannon by caliber.
Stone balls.
Heyday: 15th to 16th centuries
Iron balls and shot.
Heyday: 16th to 19th centuries
Twenty-inch (508 mm) Rodman and Dahlgren smoothbore cannons were cast in 1864 during the American Civil War. The Rodmans were used as seacoast defense. Although not used as intended, two 20-inch Dahlgrens were intended to be mounted in the turrets of and .
Explosive shells.
Heyday: 19th to 20th centuries