iron wall; impregnable fortress; impregnable; invulnerable; unassailable
wall of rock; rock cliff; rock face
precipice; cliff; flat head
quay; wharf; jetty; wall-like shoreline; cliff wall
precipitous cliff; sheer precipice; critical situation
perfect; complete; flawless
impregnable castle (walls); impregnable; invulnerable; unassailable
anterior wall; front wall
neighbor with just a wall between; neighbour with just a wall between
immediate neighborhood; immediate neighbourhood
facing a wall for nine years in meditation (by Bodhidharma at Shaolin Temple)