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Banco Bilbao Tower in Madrid by Saenz de Oiza. No rhetoric, just technology.

Short essay on the Spanish masterpiece. London, 16th November, 2020.

The American firm Skidmore, Owings & Merrill and the Italian architect Gio Ponti have been appointed as jury members to decide on a winner for a competition. The project involves the design of  the new headquarters for Banco de Bilbao in the centre of Madrid. The plot sits on the Paseo de la Castellana, the main avenue that crosses the city from north to south.

The most renowned architects in Spain have been called to compete for the project. The list include the Catalan Jose Antonio Coderch and Antoni Bonet Castellana and the Madrid based Corrales and Molezun, Rafael de la Hoz and Antonio Fernandez Alba with Antonio Miro. The winner is announced in July 1971, Javier Saenz de Oiza, the architect of Torres Blancas and professor at the School of Architecture in Madrid would be the responsible to design the tower.

The American Influence

Oiza had spent one year as a young graduate travelling around the United States and came back to Spain convinced of the importance of the technological approach in the contemporary architecture. During the competition stage, Oiza kept studying once and again three towers that had been recently completed in the American country: the Kline Biology Tower by Philip Johnson in New Haven, the Knights of Columbus Tower by Kevin Roche and John Dinkeloo and the CBS Building in New  York City by Eero Saarinen.

The interest of the design of these towers resided in the role of their structure in defining the architectural language with which these buildings expressed themselves. Concrete playing a major role in holding all of them up. Relatively small skyscrapers The Kline Tower and the CBS Building expressed themselves as rotund masses defined by their perimeter concrete structure. Roche & Dinkeloo’s tower was a megastructure composed of 5 gigantic concrete columns that supported the steel grid slabs that spanned in between them.

The design of the concept

From the first stages of the competition he set up a multidisciplinary team including the civil engineer Javier Manterola and the industrial engineer Benedicto Aguilera with whom he would discuss how to integrate the different disciplines into a coherent whole

The intention of Oiza was to propose a technological building, a design devoid of rhetoric. The most important concepts for him were a structure that could bridge over the underground train tunnels that crossed the plot, a design as energy efficient as possible and a rigorous system of dimensions and proportions that would organise the entire design, from the cladding down to the size of the lighting fixtures.


132 (cm), which was also the motto for the competition, was the chosen module for the cladding that would organise it all. 2 modules would be an office, and 1/8 of the module would be the rise of a step. As a result, the tower adopted rectangular proportions in plan of around 45.54m by 28.38m, which represent a proportion of 1.6046, very close to that of the golden ratio.

A habitable megastructure

The Banco Bibao Tower is conceived as a bridge with two massive steel reinforced concrete columns and seven post-tensioned concrete slabs cantilevering from them. The space in between these two main supports is defined by the space required to avoid punching through the underground tunnels crossing the site. At the same time each column is composed of two asymmetrical “I” sections distant enough as to create the lift lobbies in between. Six of the seven post-tensioned slabs receive the weight of the five levels built using a steel structure above them. The seventh becomes the roof and supports everything on it.

This approach to solving the structure with such a big gesture - a strategy more commonly found in infrastructure projects - brings the design of this building in close relationship with the work of Le Corbusier, Kenzo Tange and the Japanese Metabolists or even the futuristic proposals of Archigram. Considering the fact that Oiza was an indomitable studious of anything and everything around him, it is nearly impossible that these associations are a mere coincidence.  

Each façade was treated in response to its orientation. Free glass on the north, a cantilever protected the glass both in the east and south facades. The west face of the building presents second layer of green tinted glass that protects the inner one, offering shade and diminishing the solar gains of the internal space.

A flexible building

The image of the building is left to the honest expression of its spatial arrangement and the aesthetic qualities of the corten steel in combination with the brown tinted curtain wall. The sequence of typical office floors, the opaque plantroom levels and the higher floors where the post-tensioned slabs reside confer the building with a delicate and sophisticated rhythm.

The office floors, with their orthogonal grid of small steel columns can cater for virtually any office space layout that one can imagine. While the special and higher intermediate floors, completely deprived of columns materialize the dream of the continuous free plan. The building was conceived ready to stand the test of time and adapt to any future use that it may be required to cater for.

Designed ahead of its time - from headquarter to multi-tenant building

In the year 2000, nineteen years after its completion, the Banco Bibao Tower was declared BIC - asset of cultural interest from its acronym in Spanish – amidst the rumours of the possibility of it being demolished so the tower could remain as one of the city skyline symbols.

More recently, in 2018, the architecture studio Arquimania, lead by Antonio Ruiz Barbarin, was commissioned with the task to refurbish the building and turn it into a multi-tenanted office space.  According to Barbarin their main task resided in bringing back the building to its original state, stripping it off the multiple layers of past interventions that had been done without respecting the original design.

Without any technological improvement other than the restoration of the original mechanical ventilation system – which used fan coil units, cutting edge technology at the time of its construction – Castellana 81, as it is known today, has been able to achieve a LEED Platinum and Well accreditations.  A clear demonstration of the forward thinking embedded in its original design.


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