These work the same way as molly fasteners for hollow walls.

On the east side the hollow wall rises directly from the road.

This land has an inactive gravel pit against the hollow wall.

The secret door slid silently into the hollow wall, giving free entrance.

The hollow walls of the cave, when struck by hand, make incredible musical sounds.

These hollow walls are accessible from the attic and open at the top.

But on either side were doors leading into apartments within the great hollow wall.

Behind the panel was the space within the hollow wall.

Fire had spared nothing but hollow walls of stone.

The wall between them was thick; it moved up and down within a hollow wall below.