A casemate is a fortified gun emplacement or armored structure from which guns are fired, in a fortification, warship, or armoured fighting vehicle.
A mid-19th century artillery casemate at Fort Knox, Maine.
An ancient casemate wall at Masada
Embrasures for artillery casemates in the flank of a bastion at the 17th-century Citadel of Arras.
Three tiers of artillery casemates at the mid-19th century Fort Point, San Francisco
A gun turret is a mounting platform from which weapons can be fired that affords protection, visibility and ability to turn and aim. A modern gun turret is generally a rotatable weapon mount that houses the crew or mechanism of a projectile-firing weapon and at the same time lets the weapon be aimed and fired in some degree of azimuth and elevation.
A modern naval gun turret (A French 100 mm naval gun on the Maillé-Brézé pictured) allows firing of the cannons via remote control. Loading of ammunition is also often done by automatic mechanisms.
The commander's cupola of a Conqueror tank with a machine gun
BEP vignette In the Turret (engraved before 1863).
HMS Captain was one of the first ocean-going turret ships