Ramparts

noun

1. A defensive mound of earth or a wall with a broad top and usually a stone parapet; a wall-like ridge of earth, stones or debris; an embankment for defensive purpose.
2. A defensive structure; a protective barrier; a bulwark.
3. That which defends against intrusion from outside; a protection.
4. (usually in the plural) A steep bank of a river or gorge.