The Olympic site in Munich is distinguished by the lightweight cable nets of its symbolic roof construction, shaping the image and success of the “cheerful games” in 1972. The designing process of this emblematic structures was a challenge for civil engineering before the invention of high-performance computer technology. The realisation of this innovative cable nets required the cooperation of many different disciplines in civil engineering and was possible only through experiments with physical models. Of the many models used by the engineers in the 1970s, only a few have survived. The paper will describe the networks of actors in civil engineering participating in this innovative planning process and the essential role physical models played in the constructing of the lightweight cable nets for the Munich Olympic site.