This imposing 102 m high steel construction was built for the World Fair in Brussels in 1958 and became world famous within a very short period of time. It is a symbol for the peaceful use of atomic energy and represents an iron molecule magnified 165 thousand million times. The hollow spheres, 18 m in diameter, are connected by tubes 3 m wide. Via escalators visitors can get from one sphere to the next. Five spheres can be visited. They house different exhibitions.