Abstract: In an openable roof apparatus for a space, a stationary support structure is arranged about the space. A movable roof structure is supported by the stationary support structure and is movable with respect thereto. The movable roof structure having a first movable roof section and a second swing roof section. The second swing roof section is movable angularly about the central axis of the space with respect to the first movable roof section and is capable of being overlapped therewith. A guide arrangement is arranged on the stationary support structure and extends perpendicularly to a central axis of the space. The first movable roof section and the second swing roof section, which are overlapped with each other, are movable along the guide arrangement toward and away from the space.