Terreplein
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In fortification architecture, a terreplein or terre-plein is the top, platform, or horizontal surface of a rampart, on which cannon are placed,[1] protected by a parapet.[2] In Martello towers, the roof or terreplein was sometimes surmounted with one or two cannon mounted on a gun platform with a central pivot, that enabled the guns to traverse up to 360 degrees.[3]
In civil engineering works, a terreplein is an embankment of earth with a broad level top, which is sometimes excavated to form a continuation of an elevated canal across a valley.[1]