Ministerio de Defensa del Perú building, Army headquarters in San Borja, Lima, Peru

The Ministry of Defense building is a government structure in San Borja characterized by bold concrete forms and sharp geometric angles. It spans multiple levels with a central administrative tower connected to several outlying wings.

In January 1971 General Ernesto Montagne Sánchez, army commander and war minister, ordered a new headquarters to centralize the dispersed War Sector bodies. The 949,696 m² site in Chacarilla del Estanque, then Surco and now San Borja, was chosen in April 1971. The Tanaka-Chueca-Mesía firm designed the complex, built in six sectors from December 1973; President Juan Velasco Alvarado inaugurated it on 22 January 1975, and it began operating in mid-1976.

The building stands as an example of brutalist architecture in Peru, demonstrating the international influence on South American military construction during the 20th century.

The building is located in a business district of southern Lima and can be reached by public transportation. Visitors should be aware that this is a secured government facility with restricted access to certain areas.

The nickname 'Pentagonito' refers to the Pentagon in Virginia, but the complex is not pentagon-shaped. It functions as the de facto main square of San Borja. The site covers 949,696 m², and planting inside and outside was planned to turn the area into a green 'lung' for the district.