Amid the traffic and bustle of central Mexico City, the fortresslike Ciudadela building sprawls territorially across its 7-acre parcel of land, bordered by the busy Balderas Avenue and bright yellow vendor carts to the east, a smaller street to the west, and public plazas to the north and south. Tucked within its stone confines, along the building's northwest perimeter and facing an interior courtyard, is the diminutive Antonio Castro Leal library, a newly renovated space designed by Mexico City–based BGP Arquitectura to house the private collection of the Mexican intellectual, diplomat, and National University president who died in 1981.
A single-story structure built on a square plan, La Ciudadela has a history that is as rich as its walls are thick. Commissioned by the Spanish crown at the end of the 18th century, the building, which rests on a robust vaulted foundation over swampland, started its life as a tobacco-processing facility—the four large courtyards at its center were used for drying leaves. Through the 19th century the building served as a military post, an arsenal, and a hospice for the poor. It earned its name La Ciudadela (The Citadel) in 1885, when it became the northern barracks of the city garrison. Later it was used for weapons manufacturing, and then, in the 1940s, part of the building was turned over to the nation's general archive and another part to the National Library. In the 1960s other cultural and educational institutions moved in to share the space. More recently, in 1987, Mexican architect Abraham Zabludovsky enclosed the main courtyards with enormous steel canopies to create reading rooms and file storage.