The retail and business centre in Frankfurt is covered by a stunning glass roof with an overall surface of approx. 12,000 m2. M. Fuksas’ design idea for the roofing is based on the shape of a canyon, running between the buildings. An airy and delicate shell structure has been achieved by the use of form-active elements and by breaking-up the free-form surface into triangular shapes. Standardized methods and tools did not exist or didn’t lead to satisfying results. At first the orientation of the members had to be achieved which satisfied aesthetic as well as structural and functional requirements. In a next step the shape was divided into mega triangles indicating the location of special nodes and then subdivided into smaller triangles. The executing company proposed a welded connection for the node which was fabricated out of a thick steel plate. In order to minimize welding on site, ladders were prefabricated in the workshop. The sections are welded rectangular hollow sections 120 x 60 mm. The thickness of the plates is adapted to the respective local loading conditions.