Battlements were most often found surmounting curtain walls and the tops of gatehouses, and comprised several elements: crenellations, hoardings, machicolations, and loopholes. Crenellation is the collective name for alternating crenels and merlons: gaps and solid blocks on top of a wall. Hoardings were wooden constructs that projected beyond the wall, allowing defenders to shoot at, or drop objects on, attackers at the base of the wall without having to lean perilously over the crenellations, thereby exposing themselves to retaliatory fire. Machicolations were stone projections on top of a wall with openings that allowed objects to be dropped on an enemy at the base of the wall in a similar fashion to hoardings.