There are many openings in the rock wall.

VOA: special.2010.07.05

When the external factors of a city's environment require the wall to be without openings, the interior must be especially full and satisfying.

ECONOMIST: Museum architecture

Pierson to observe that the openings read as if cut out of the wall rather than as heavy piers supporting a pediment.

WSJ: Prim Grandeur, Elegant Geometries | Charles Bulfinch | Lancaster Meetinghouse | By John Wilmerding