tension was then applied to internal post-tensioning cables running in all three dimensions, locking the structural elements into place something like a child's toy that is floppy until its parts are pulled together tightly with a string. There were a total of 1019 of these structural elements, and for the post-tensioning to be effective, they had to be precisely dimensioned and perfectly formed. Komendant worked closely with the manufacturer to ensure that outcome, with the result that the largest offset between any two elements in the finished structure was only . In line with his belief that structure should be made visible, Kahn exposed these structural elements on the building's exterior and in the laboratory ceilings. He also left the ceiling of the entry porch open so the public could inspect the structure there, including the Vierendeel trusses that Komendant engineered to support each floor. Looking something like ladders turned on their sides, these trusses have large, rectangular openings that make it easy to thread pipes and ductwork into the laboratories. Despite significant shortcomings from the viewpoint of the scientists who worked there, the building won international acclaim not only for its architecture but also for its innovative building techniques. In 1961 the Museum of Modern Art sponsored an exhibition devoted exclusively to this building, describing it in a brochure as "probably the single most consequential building constructed in the United States since the war". Architectural historian Vincent Scully said the pioneering work by Kahn and Komendant on this project "was to affect for good the techniques of the whole concrete pre-casting industry from the factory to the site." The Architectural Record noted at the time that the precision achieved was "more typical of fine cabinetwork than of concrete construction." Salk Institute for Biological Studies At the Salk Institute for Biological Studies (1959–1965) in La Jolla, CA, the need for mechanical services (air ducts, pipes, etc.) was so extensive that Kahn decided to create a separate service floor for them above each laboratory floor to make it easier to reconfigure individual laboratories in the future without disrupting neighboring spaces. He also designed each laboratory floor to be entirely free of internal support columns, making laboratory configuration easier. Komendant engineered the Vierendeel trusses that make this arrangement possible. These pre-stressed concrete trusses are about long, spanning the full width of each floor and extending from the bottom of each service floor