The construction of the Atomium was a technical feat. Of the nine spheres, six are accessible to the public, each with two main floors and a lower floor reserved for service. Tubes of 3 metres (10 ft) diameter connect the spheres along the 12 edges of the cube and all eight vertices to the centre. The central tube contains the fastest elevator of the time with a speed of 20 ft/s. It allows 22 people to reach the summit in 23 seconds. The escalators installed in the oblique tubes are among the longest in Europe. The biggest is 35 metres (100 ft) long.
Three of the four top spheres lack vertical support and hence are not open to the public for safety reasons, although the sphere at the pinnacle is open to the public. The original design called for no supports; the structure was simply to rest on the spheres.
The Atomium, designed to last six months, was not destined to survive the 1958 World Expo, but its popularity and success made it a major element of the Brussels landscape. Its destruction was therefore postponed year after year, until the city's authorities decided to keep it. However, for thirty years, little maintenance work was done.
