Room rotation?

For a project I wish to rotate a room that is constructed of 6 different planes (Ceiling, 4 walls, floor). I know I can change the gravity of the room easily through the Physics.gravity, but how would I change the rooms orientation?

Essentially I want to rotate the room 90 degrees around the X or Y axis, what would be the easiest way to accomplish this?

Through a common parent. Set everything child of an empty game object in the middle of your scene, then rotate it.