A landmark building, originally constructed for the 1958 Brussels World Expo. It is located on the Heysel Plateau, where the exhibition took place. Designed by the engineer André Waterkeyn and architects André and Jean Polak it stands 102 meters tall.
Its nine 18 meters diameter stainless steel clad spheres are connected, so that the whole forms the shape of a unit cell of an iron crystal magnified 165 billion times. The five habitable spheres, which contain exhibit halls and other public spaces. The top sphere includes a restaurant which has a panoramic view of Brussels.