The pillars are mushroom-shaped for two reasons. The first is utilitarian; the floors were constructed beamless for better daylighting and, thus, light reflection (beams cast very long shadows). This has the additional advantage of simplifying the placing and moving of cables and lighting fixtures. And the mushroom shapes give an impression of greater height. The second, constructional, advantage is that the steel bundle reinforcement in two directions makes the structure equally rigid in all directions. Since future mining activity was impossible to predict, a large resistance in all directions to sagging was desirable.