defensive structure consisting of walls or mounds built around a stronghold to strengthen it

a fortification composed of many projecting triangular bastions (usually from five to eight), specifically designed to cover each other; first seen in the mid-15th century in Italy.

in military architecture, a bastion constructed of one face, and one flank.

a type of bastion used in the 16th century; fell out of favor because of the difficulty of concentrating the fire of guns distributed around a curve.

a bastion that is filled up entirely, and has the ground even with the height of the rampart, without any empty space towards the center.

a fortification composed of many projecting triangular bastions (usually from five to eight), specifically designed to cover each other; first seen in the mid-15th century in Italy.