Lightwell

In it a covered porch and vestibule were backed by a vertical shaft or "light-well," which served as a great window both to the vestibule itself, and to the corridors, staircases, and landings that connected it with the upper stories.

The sliding glass door with its rolled-up blinds looked onto a lightwell, composed of a glass platform overhead and carefully angled mirrors that were reflecting a confusing cold light into the bedroom.