Between 1950 and 1955, the United States Embassy in Madrid was planned and built on the former Huerta de Cánovas estate. This building has already been studied in its pioneering and controversial implementation in the Paseo de la Castellana. Some reference has also been made to the link between Mariano Garrigues, the Spanish architect who directed the construction works, and North America. This article goes deeper, however, into some issues that have not yet been explained; in particular, the aim is to reveal how a prototype of the International Style was adapted to local circumstances. For this purpose, both foreign sources related to the North American architectural office (Foreign Building Operations, FBO) and local sources related to the Spanish architect are used. Likewise, graphic analyses are carried out to complement the available information and to focus on aspects of the site, construction, and spatial organization. The analysis is not limited to the general aspects of the building. Its link with post-war modern architecture is increased with considerations of site, structure and furnishing. The final assessment falls somewhere between absolute adherence to modern ideals and local mediation.