This unique space, charged with artistic and symbolic force, was designed to fulfill a functional role and bears no semblance to the architecture of its time. The astonishing set of architectural-sculptures placed here falls into three kinds of structures: stairwells, ventilation towers and chimneys. Some are covered with trencadís (ceramic fragments), while elements that are the less visible from the street are only roughcast-rendered and painted. The undulating balustrades conform to the shape of the façade, as Gaudí sought a harmonic solution between the rhythms of the façade and the finishings of the roof.