The Libertador Building (Edificio Libertador) is a government building in Buenos Aires, Argentina, housing the Ministry of Defense. The rapidly growing and modernizing Argentine military of the 1920s, whose budget had risen threefold in the decade, lacked a commensurate headquarters, and had been housed since the late 19th century in a Montserrat neighbourhood structure formerly used by the National Mint. Seeking to remedy this, President Agustín Justo (a retired general and former War Minister) ordered the construction of a new War Ministry, and commissioned Carlos Pibernat, chief architect of the General Engineers' Office, for its design.
Pibernat's plans, submitted in 1935, called for twin buildings east and west of the of the presidential offices at the Casa Rosada. Ultimately, however, these plans were dropped in favor of imposing new headquarters on a 3 ha (8 ac) lot east of the Casa Rosada. Designed by Ministry of Public Works architects Enrique Lopardo, Néstor Pastrana, and Héctor Campini, the twenty-story, 82,625 m² (889,000 ft²) building would be the largest in Argentina up to that point. The building would thus be divided into three sections: two wings to be anchored by a central section staggered outwards in the 230 m (750 ft) long façade, and distinguishable also by a portico and its four additional floors.
The structure, designed in French Renaissance style and begun in 1938, was equipped with Siemens elevators and communications networks, whose installation was overseen by German engineers. Following the installation of security systems, libraries, archives and a tunnel connecting the building to the Casa Rosada, as well as the lengthy and politically sensitive process of assigning wings and pavilions to the myriad Argentine military bureaus, the new War Ministry was inaugurated in April 1943.