The tower is one of the first to rely substantially on craftsmanship, with the final appearance being one with a high degree of linearity captured in stone. While previous façades were certainly drawn prior to construction, Strasbourg has one of the earliest façades whose construction is inconceivable without prior drawing. Strasbourg and Cologne Cathedral together represent some of the earliest uses of architectural drawing. The work of Professor Robert O. Bork of the University of Iowa suggests that the design of the Strasbourg façade, while seeming almost random in its complexity, can be constructed using a series of rotated octagons.