Situating itself in current debates over the international legal archive, this article delves into the material and conceptual implications of architecture for international law. To do so I trace the architectural developments of international law’s organizational and administrative spaces during the early to mid twentieth century. These architectural endeavours unfolded in three main stages: the years 1922–1926, during which the International Labour Organization (ILO) building, the first building exclusively designed for an international organization was constructed; the years 1927–1937 which saw the great polemic between modernist and classical architects over the building of the Palace of Nations; and the years 1947–1952, with the triumph of modernism, represented by the UN Headquarters in New York. These events provide an illuminating allegorical insight into the physical manifestation, modes of self-expression, and transformation of international law during this era, particularly the relationship between international law and the function and role of international organizations.