terreplein

noun4

1. •
   The level platform atop a wall, typically protected by a parapet and (strictly) distinguished from the slightly higher banquette used by its defenders.
2. •
   Any level base used by artillery in the field.
3. •
   Any earthen embankment with a broad level top, such as those used for a canal elevated above a valley floor.
4. •
   (no longer used) The sloping earthen embankment behind a defensive wall.