Bastion n. : A work projecting outward from the main inclosure of a fortification, consisting of two faces and two flanks, and so constructed that it is able to defend by a flanking fire the adjacent curtain, or wall which extends from one bastion to another. Two adjacent bastions are connected by the curtain, which joins the flank of one with the adjacent flank of the other. The distance between the flanks of a bastion is called the gorge. A lunette is a detached bastion. See Ravelin.

Example:
How do I get back to Hollow Bastion on Kingdom Hearts?

Taxonomy
bastion, castle, Bastion fortress, Hesco bastion, free encyclopedia, fortifications, flanks, gorges, curtain, rampart, troops, ground, parapet, court, tenaille, acute, polygon, search.

Defination from the web:
bastion is a structure projecting outward from the main enclosure of a fortification, situated in both corners of a straight wall (termed ... Area denial weapons · Barbican · Balistraria · Bastion · Caltrop · Castle · Concentric castle · L-plan castle · Water castle · Cheval de frise ...