Woman from Another Planet by Frank Belknap Long

David Loring only knew at first that the room in which he found himself was enormous. He could see the high walls towering up into shadows, and the great distance which separated wall from wall, shadow from shadow.

He saw the room in fitful flashes, between sleeping and waking. He saw it as a prison and a sanctuary, the ward of a hospital, a waiting room at the hub of some intricate and planet-engirdling web of communication. He saw it even as a quite simple, peaceful place, soothing to the eye, where a man could sleep and dream with a beautiful woman at his side, their bodies completely at ease in the dawn light, relaxed and languorous.