On the ground, the steel structure consists of three adjacent compressed rings, which are connected by spokes made of round tube profiles. The outer ring is in the form of a three-dimensional structure. Suspended in between are vertical “air supports”, which run up and down in the shape of a pyramid, attached by four tension rods each. In addition, the entire steel structure is undergirded by tie rods which run from the edge beams across the air supports to the inner tension ring. The pneumatic cushion is composed of two layers of membrane, manufactured from PVC-coated polyester material, which is assembled and mounted in a single unit. The lower membrane is supported at the edge by 56 air supports and a cable grid, while the central area with a diameter of 40m is an unsupported span. The upper membrane stretches across the entire ellipse. It is held in place by 28 radial cables that rest on the outer membranes. These cables are protected from the weather by sleeves. Two blower stations keep the air pressure at 379Pa. Sensors mounted inside the membranes respond to weather conditions and control the pressure in the membrane up to a maximum of 1,000Pa. The attic’s circumferential aluminium cladding forms the outer end of the roof.