The Atomium in Brussels’ Heysel Park was built for the 1958 World’s Fair. Resembling a giant executive toy, it represents an iron crystal molecule, with each of the nine steel spheres symbolizing individual atoms. The spheres, each 59 ft (18 m) in diameter, are connected by tubes containing escalators, and the topmost one, at a height of 335 ft (102 m), offers visitors a panoramic view over the city and surrounding area. The structure underwent renovation in 2006, financed in part by selling as souvenirs pieces of the metal sheeting that originally covered the spheres.