In 1928 Le Corbusier drafted detailed plans for a centre of information, science, and education, called the Mundaneum, to complement the headquarters of the League of Nations in Geneva. The allegedly historicist and academic traits and quasi-religious tendencies of these plans triggered fierce reactions by critics such as Karel Teige and El Lissitzky. Le Corbusier in turn answered these critiques in a long essay entitled "In Defense of Architecture". This paper aims to shed new light on the Mundaneum debate by exploring the programme of the Mundaneum as it was defined by the Belgian documentalist and utopian internationalist Paul Otlet (1868-1944) and translated in architecture by Le Corbusier. Otlet conceived the Mundaneum as at the same time a concept of a new kind of information service that would eventually absorb libraries, and a complex of institutions that he and Henri La Fontaine directed and had brought together in the prestigious Palais du Cinquantenaire in Brussels. The Mundaneum was his lifelong project in which the design of Le Corbusier was only one, although an important, moment in its development, followed by a series of designs made by Belgian modernist architects in the 1930s and 1940s. By entering into a dialogue with the history of information science, the history of internationalism, and especially the history of positivism in all its spirituality, this paper reinvestigates the symbolism of the spiralling pyramid of the Mundaneum as designed by Le Corbusier and his followers.