The ceiling beams are functional as well as decorative, as they double as walkways enabling technicians to reach the elaborate lighting system without the need to resort to scaffolding.  The lighting for the naturally-lit gallery spaces is carefully controlled using external louvre blinds which open and close automatically in response to the brightness of the sky.  This ensures that the galleries are always lit to an optimum level, whilst maintaining the conservation light levels required to preserve the works of art.