Conning tower
The Devastator, an Imperial I-class Star Destroyer, featured a command tower as seen here.
Command towers, also known as conning towers, were external structures housing the bridge on various warships belonging to the Galactic Empire. The Imperial II-class Star Destroyer was one such Imperial vessel that incorporated a conning tower. During the Battle of Hoth, the conning tower of the Tyrant, an Imperial II-class Star Destroyer, was destroyed by an ion cannon blast fired from the Rebel Alliance's v-150 Planet Defender. Due to the exposed nature of these command towers on Imperial warships, the Resurgent-class Star Destroyer of the First Order did not include them in its design.
Imperial-class Star Destroyers
The command tower of Imperial-class Star Destroyers housed either a tractor beam targeting array (on Imperial I-class Star Destroyers) or a communications tower (on Imperial II-class Star Destroyers and modernized Imperial I-class vessels), and was accompanied by two deflector shield generator globes on either side.