The author of this article, a partner in the Swiss Engineering Office of Realini+Bader at Geneva, has studied the economic aspects of multi-storey car parks using a comparative analysis of five different examples from his own country. Decision making factors are, he says, the kind of building (underground or not), the number of square metres per car, the free span between columns, the number of floors, the type of flooring. The kind of building is the most important factor, the type of flooring the least important.