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Plaza de Armas Metro Station: A New Urban Hall


Santiago, Chile

October 2019


Alejandro Beals, Loreto Lyon


Raúl Avilla, Nicolás Frenkiel, Gonzalo Torres, Andrés Lira




Pablo Casals


While the project itself is not below ground, it is governed by the idea of surfacing the spatial condition of the subterranean, remaining in dialogue with the Cathedral and its crypt, the Plaza de Armas and related public spaces. To be part of this system, the project aims to build a memorable public space: an urban hall with a clear span of 23 metres.

The structural solution de-emphasised weight and mass, through a sequence that combines two types of vaults of alternating widths (3.6 and 7.2 metres), supporting the upper floors. In turn, each vault is formed by smaller double-curved formwork modules. Any areas in the structure with lower degrees of stress are infilled with big polystyrene spheres, in order to remove mass.

On top of the concrete plinth there is a volume that is delicate yet heavy: a box made of a light concrete grid, glass and alabaster. This façade gives an opaque and monolithic appearance from the exterior, while permitting natural and even light to flow into open plans to be used as new office space by the client, Metro de Santiago.

The volume recomposes a continuous facade in dialogue with the surrounding buildings. The porous plinth, rough in its monolithic structural expression, withstands the enormous friction with the city that metro stations endure – the heavy use, the traffic, the absence of care. It is a hard, stable base on which something more delicate rests: a petrous lantern that will announce the public purpose of the building.


In October 2019, protests erupted in Chile’s capital, Santiago, in response to increases in the cost of metro tickets. High school students jumped turnstiles en masse, accessing the platforms without paying and clashing with the police. Within a few hours, thousands of people filled the streets to demonstrate their frustration with the wider neoliberal economic model. The metro system was at the core of the conflict and about twenty stations in Santiago were partially burned.

Just a couple of weeks before the protests began, this metro station opened in the historical centre of Santiago, an area that was undergoing an intense process to consolidate its heritage and pedestrian character.

The first metro line in Santiago was inaugurated in 1975; since then, five other lines have been built, within a continuous process of expansion to link the city centre with parts of the city otherwise disconnected. This station adds to the newest line, connecting to the north-west of the city.

The station’s heavily restricted plot is mostly filled with the reinforced-concrete structure connecting street level with the tunnel of the metro line below. This left little room to locate the ticket offices and turnstiles close to the tracks, as is the case throughout the city’s metro system; stations are signified above ground by just a staircase, similar to the New York subway. A first in Santiago, the project creates a station at street level, assuming a role as a public space that could be seamlessly integrated with the city’s historical fabric.


The station itself suffered little damage during the social unrest (some broken glass and other minor incidents). The building’s plinth, made of rough concrete, was equipped with metal bars added to the design at a later stage. The building can withstand social and political turmoil while still supporting the delicate alabaster facade of the office building above.

Chile is a country with high levels of inequality, and Santiago is a segregated city. As a public service, the metro system is fundamental in connecting segregated areas, bringing its many lines into the city centre, to emerge, as in this case, as a piece of public architecture and not just infrastructure. The metro has become both a symbol of social unrest and of social integration. The project plays a role within this larger network, as an agent of social transformation at a symbolic level.

The symbolic, a purpose once fulfilled in architecture by the ornamental, has been transferred, since the rise of modern architecture, into the tectonic expression of construction. In this project, the symbolic expression articulates multiple contrasting situations: between the subterranean (tracks) and the terrestrial (station); the monolithic (plinth) and the porous (building); the harsh (base) and the delicate (facade); the curvilinear (vaults) and the orthogonal (block); the periphery (greater Santiago) and the historical (city centre).

The building operates as a manifold that dialectical interplays to articulate these opposites, combining divergence and juxtapositions in a coherent, seamless architecture which becomes part of the network of public spaces in the city.

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