Siege artillery were heavy guns and other bombardment devices designed to bombard fortifications, cities, and other fixed targets. They were capable of firing heavy cannonballs or shells but required enormous transport and logistical support to operate. They lacked mobility and thus were rarely useful in more mobile warfare situations. They have been generally superseded by strategic bomber aircraft and surface-to-surface missiles in modern warfare.
References
List of siege artillery Wikipedia(Text) CC BY-SA