French 370 mm railway howitzer of World War I

A railway gun, also called a railroad gun, is a large artillery weapon, built on, transported by, and fired from a specially designed railway wagon. Many countries have built railway guns, but the best known were made by Krupp and used by Germany in World War I and World War II. Smaller guns were often part of an armoured train.

Railway guns are no longer used. Their large size and limited movement made them easy targets. They have been replaced by aircraft, rockets, and missiles.