The Kansas City Office Building – never built but designed in many variations between 1966 and Louis Kahn’s death in 1974, in close collaboration with the structural engineer August Komendant – is a clear example of the poetics of weight and mass in contrast with prevailing ideals of structural lightness. In their final solution, Kahn and Komendant hang the slabs of the entire building from the catenary structures at the roof, which themselves hang from the massive corner columns. Kahn, always using drawing as a means of thinking, here deliberately leaves the middle of the tower structure void to emphasise the structure and weightlessness of the building and the urban scale of the social facilities ground floor.