"Cement Hall, Swiss National Exhibition, Zurich (1939)... was built by architect and engineer Hans Leuzinger and ... to demonstrate the potential of thin shells. ...The width of this parabolic shell is 50.32 ft... built by the Gunite method, [it] is only 2.36 in thick. ...A sculptural piece by Robert Maillart entititled "Endless Ribbon" [1935-1936]... is a thin shell built of reinforced concrete. This... can be classified within Constructivism or... constructive spatial art. [I]t represents... the direct correlation between the language of sculpture and that of modern thin-shell architecture that moves the sensitive engineer such as Maillart to express himself also as a sculptor. Maillart's structural shells as a whole testify to this similarity of language... He was the father of flared columns connecting with floor slabs to eliminate supporting beams and designed unique bridge forms. Maillart's name remains associated with innovative concrete forms that extend to the structural virtuosity of thin shells."