Building at Paseo de la Castellana 81, in Madrid

The AZCA complex was conceived by the 1946 Madrid General Urban Planning Plan, commonly called the Bidagor Plan. It was developed from a project by the architect Antonio Perpiñá, winner of the international competition called in 1954. The definitive Partial Plan for the superblock was definitively approved by COPLACO in 1964.

In 1971, Banco de Bilbao, owner of plot number 41 of the complex, called a restricted competition for the project of the building for its headquarters in Madrid, with a tower typology, among seven of the most prestigious Spanish architecture studios in The time. The guests were Antonio Bonet, José Antonio Coderch, José Antonio Corrales and Ramón Vázquez Molezún, Antonio Fernández Alba, Rafael de la Hoz and Gerardo Olivares, Antonio and Manuel Miró and, finally, Francisco Javier Sáenz de Oiza.

The projects had to solve the challenge of erecting a thirty-story office building saving the vault of the tunnel of the railway link between the Atocha and Chamartín stations. The competition had three juries, one of a banking nature to evaluate the functionality of the solutions, another purely technical for structural and technological aspects, entrusted to the American firm Skidmore, Owings & Merril (SOM) and a third for formal and aesthetic issues , entrusted to the prestigious Italian architect Gio Ponti.

Sáenz de Oiza's proposal was based primarily on the search for an optimal structural response to such a complex problem. For this he had the collaboration of engineers Carlos Fernández Casado, Javier Manterola and Leonardo Fernández Troyano. It was decided that the structure would be mixed, made of steel and reinforced concrete. The entire weight of the building was transferred to the ground through the foundation of two powerful concrete cores, located on both sides of the tunnel, solving the transmission of loads to those two cores by stacking five-storey buildings, in each of which the lower floor was a slab on a grid of large cantilevered concrete beams, which collected loads from the metal pillars of the four upper floors. This structural system determined
the existence of plants of different heights, which favored the creation of horizontal rhythms on the facades. The chosen system allowed the existence of a plant without pillars in each group of five, which would have a greater free height to save the drop of the concrete beams.

As for the closings, the architect decided his total autonomy with respect to the vertical structure, which was set back around the entire perimeter, allowing a uniform solution, without interruptions or edges, with curved corners.

For its comprehensive design, it rigorously and obsessively adopted, both in plan and elevation, a 33-centimeter module, the “elephantine foot”, whose multiple of 1,32 meters was the basis for composing the plans. Modulation in the design process was so decisive that this grid length was used as the motto of the project. All the exterior and interior elements were adapted to the module, from the composition of facades at the height of the stair treads or to the cutting of floors or false ceilings.

Once the prismatic shape of the tower was decided, the type of support on two nuclei separated from each other naturally led to the choice of a rectangular plan in the east-west direction, which determined that the main facades would be perpendicular to the axis of the promenade of the Castilian.

More or less direct influences for this project can be traced in postwar American architecture. The most obvious one is the SC Johnson and Son Research Tower, built by Frank Lloyd Wright between 1944-1950 in Wisconsin, organized around an internal concrete core, with uneven slab trays and autonomous exterior skin with curved corners.

The contest was resolved in 1972 in favor of Sáenz de Oiza's proposal. The execution project was developed between 1972 and 1974. The specific use and activity foreseen in the municipal license was commercial, offices and parking. The works began in 1975 and ended in 1981.

Throughout its brief history, initially as the headquarters of the Banco de Bilbao and later as the headquarters of the banking entities that emerged from successive mergers, the building remained unchanged, except for the corporate logos on the coronation corps. However, on the inside there were specific alterations, the most evident of which was the silting of the waiting spaces in the mezzanine. In 1991, an exhibition and conference room was installed in the basement. In 2000 a new emergency stair case was added on the west side that had no influence on the envelope.

In 2007, it was sold by the bank BBVA to the real estate company Gmp Property Socimi SA, which proposed a comprehensive rehabilitation of the building to restore its original characteristics. In 2014 the general works of conservation, restoration and adaptation to the regulations of the building began, according to the project of the architect Antonio Ruiz Barbarín, based on the original documentation of Francisco Javier Sáenz de Oiza, with absolute respect for his intentions.

In these works of recovery of the original characteristics, the reconstructed elements have been incorporated following criteria of differentiation, as recommended in international restoration charts, respecting the form but using other materials or finishes.

Francisco Javier Sáenz de Oiza was born in Cáseda (Navarra) in 1918 and died in Madrid in 2000. He graduated from the Escuela Técnica Superior de Arquitectura de Madrid in 1946, traveled to the United States on a scholarship from the Royal Academy of Fine Arts of San Fernando, where it was influenced in general by American architecture, but most especially by Frank Lloyd Wright.

He was awarded the National Architecture Prize in 1946 for the project to reform the Plaza del Azoguejo in Segovia and in 1954 for a Chapel on the Camino de Santiago, in collaboration with José Luis Romaní and Jorge Oteiza.

During the first years of his professional career he collaborated with Luis Laorga in several national architecture competitions, winning first prize in those of the Hispano-American Basilica of Mercy in Madrid (1949) and the Basilica of Our Lady of Aránzazu in Oñate (1949 ), both built. Simultaneously he devoted himself to the development of proposals for residential architecture and social housing, such as the Poblados de Absorción de Fuencarral A (1955), Entrevías (1956) and Batán (1960).

In the 60s, he received the firm support of the builder Juan Huarte, for whom he built one of his unique works, the Torres Blancas building, clearly attached to Wrightian organic architecture. His career as an architect continued with other great projects, keeping in parallel an important teaching work, becoming a benchmark for what was called the Madrid School.

The building on Paseo de la Castellana, number 81, in Madrid, is a free-standing tower 107 meters high that extends laterally to the north in a low body of three floors that is attached to the adjoining plot. It is distributed in thirty-seven levels of plant, thirty-three above ground for offices and shops and four below ground for parking garage and facilities.
The lower level of the basements, commercially called the third basement, is divided into two sectors by the railway tunnels. The upper level of the basements, commercially called the semi-basement floor, has shared use of the garage and offices, with the auditorium and meeting rooms being located in it.

Above ground, the thirty-three floors are organized by seven powerful reinforced concrete structural platforms, which coincide with the floor slabs of the second, seventh, twelfth, seventeenth, twenty-second, twenty-seventh and thirty-first floors. These platforms constitute the support of the metallic substructures that make up the rest of the floors.

Within this structural scheme, there are plants with different character, use and free height. Thus, the ground floor is set back around the perimeter of the tower, hiding its contact with the ground and avoiding the existence of a plinth in the traditional way. The twelfth, twenty-second and thirty-first floors are technical mezzanines with restricted access and reduced free height, blind to the outside. The first, sixth, eleventh, sixteenth, twenty-first, twenty-sixth and thirtieth floors, located under the concrete platforms, have greater free height, with the colored concrete structure in a brown tone as a roof. In turn, the thirty-first floor and the two towers that make up the thirty-second floor are hidden by a latticework of horizontal profiles of cut steel, as a finish or crowning.

The facades of the tower clearly show the organization of the interior levels by alternating corten steel-clad breastplates and glazed bands with bronze-tinted windows. The aluminum joinery is also hidden by the corten steel plates screwed to the profiles. Maintenance walkways run the entire perimeter of the tower on each of the levels, marking horizontal lines. On the east, south and west facades, the effect is dramatically reinforced by tramex trays that have the function of reducing direct sunlight.

The tower thus acquires the appearance of a fortress executed externally only with two chromatically toned materials, corten steel and glass, with a series of complex horizontal rhythms whose irregularities are not the result of whim, but rather a response to technical and functional requirements.

Those same differences or irregularities that appear from floor to floor are seen between the different facades, which incorporate the necessary elements to satisfy specific needs for sunlight control. Thus, the west façade includes a second level of green tinted windows to reduce the annoying setting sun, and the north façade is bare of parasols for not being necessary.

The architect ensures that despite these differences or peculiarities, the building does not lose unity or formal and compositional values. This way of projecting, in which each element adapts or modifies what is necessary to respond to a specific need, approaches this building in a subtle and less evident way than in the White Towers of the same author, to the concept of organic architecture.

One of the peculiarities of the building is its implantation on the ground. The architect chooses to create a depression in the eastern and southern outdoor spaces of the plot, arranging platforms at different levels. The tower sinks into the ground and is surrounded by an authentic English patio, disappearing the traditional basement. The entrances to the building are raised at various points on the contour and with different character. Two accesses are located under the east and south facades of the tower, hidden by the setback of the ground floor, while in the lateral body there is a more representative and conventional entrance at ground level of the street.

Inside, the ground and first floors, which make up the public part of the building, form a complex spatial unit, with voids and connecting stairs. Various materials and colors are used in this area to provide an environment of greater richness and formal interest.

The tower plan is organized around the axis made up of the two concrete cores, occupied by eight lifts, and the rest of functional elements such as stairs, toilets, skids and supplementary lifts. Originally, the office spaces formed a ring around this central axis, but the introduction in 2000 of a third emergency staircase has cut the ring to the west.

Office spaces are characterized by their cleanliness and transparency. The air conditioning is distributed by continuous aluminum consoles that constitute the façade breastplates, releasing the false ceilings. In these, the modulation is manifested with powerful exposed extruded aluminum profiles and acoustic panels where the luminaires are fitted, made to measure for this dimension. The metal pillars that appear in the type plants are clad in cylindrical stainless steel sheaths welded and polished by hand.

The modulation of the facades makes it possible to subdivide the interior spaces, attaching directly to the glass separation mains and the false ceiling profiles, maintaining order and coherent design in all spaces.

In conclusion, the building of the Paseo de la Castellana, number 81, in Madrid, is a unique work within the recent architecture of the Community of Madrid for various reasons, including its original structural conception, its general proportions drawn from classical theories on beauty, a careful design supported by a rigorous study of dimensional modulation of all its parts and a correct choice of materials, all within the strictest modernity at the time of its construction. Its location in one of the most outstanding plots of the great axis of the Paseo de la Castellana ensures a presence in the urban landscape with the character of a first-rate architectural landmark. For all these reasons, it is considered to have the architectural values ​​provided for in Article 2 of Law 3/2013 on the Historical Heritage of the Community of Madrid for its declaration as a Property of Cultural Interest in the Monument category.