Battleships featured heavily armoured towers, that were called Conning Towers. They were used to protect important systems and personnel, that were associated with controlling the battleship, and targeting its naval guns (usually only their primary armament). Conning towers could have armour up to 15 inches thick, with small view slits in their armour (where crew members would look out). In battle, it was believed that Admirals and Captains would command their battleships, whilst being protected by the thick armour of their conning towers. In reality, few commanders seem to have commanded their battleships from inside their conning towers - preferring instead to command from non-armoured parts of their battleship's superstructure. The terms superstructure and conning tower are often confused! The term superstructure refers to all of the structures located above the deck of a battleship (not including its naval gun turrets). Whilst the term Conning Tower usually refers to the heaviest armoured part of a battleship's superstructure.
HMS Hood 1937 - Front Conning Tower
Here we can see, what I regard as HMS Hood's front conning tower:
Though technically the term conning tower, only applies to the elliptical structure on the front (with the rest being superstructure). The conning tower itself, was concerned with the aiming of the primary armament 15 inch naval guns. It was protected by armour of up to 11 inches thick: to ensure that Hood's 15 inch naval guns, could be aimed and fired, even in the heaviest action. The superstructure itself, was concerned with both the manoeuvrability of HMS Hood (such as steering and navigation), and further fire control (for both the secondary armament, and anti-aircraft guns). The superstructure was soft (aka thinly protected), to save armour weight. It included such equipment as: search lights, 3 pounder saluting guns, quadruple 0.5 inch anti-aircraft guns, eight barrelled two pounder anti-aircraft pom-poms directors, 5.5 inch secondary armament directors, evershed transmitters and air defence platform equipment (e.g. binoculars).
HMS Hood 1937 - Front Conning Tower - Lower Levels
Here we can see the first, second and third decks of HMS Hood's front Conning Tower Superstructure:
Of particular interest are: i) The quadruple 0.5 inch anti-aircraft guns. These were designed to put up a wall of fire, that it was believed, would help disintegrate enemy aircraft (that were targeting the bridge). ii) The 3 pounder saluting guns. These were a peace time addition, mainly used when conducting ceremonies - that were removed in times of war. iii) The secondary armament (twelve 5.5 inch naval guns) fire control directors - the rotatable cylinder with a view slit in the front. iv) The various signal search lights, which were used to communicate visually, with other warships.