For the Cologne architect Oswald Mathias Ungers (1926–2007), owner of a famous collection of books on architecture, who also repeatedly addressed the theoretical aspects of building, the construction of his own house, in 1958/59, was more than a private adventure. For him it meant a chance to gain spatial experience and explore what was possible. It was a laboratory, »a little universe«, »a piece of world«. Three decades later, Ungers expanded the cataract of forms of his first home by adding a geometrically strict cube, intended to house his library. The shock aesthetics of the early work had evolved into the rigorous abstractness of his late work.