Below ground, the building occupies the entire plot. Above ground, the building is 25 metres deep, following the criteria established in the planning regulations. The program is organized by floor, depending on the degree of access control of the different uses of the building. The ground floor, first floor and part of the first basement floor are for free access public uses: the main lobby, reception area, and several exhibition rooms that can also be used as a multifunction space. Through the lobby on the ground floor, the garden is accessed, a space designed to accommodate different uses such as open-air exhibitions, a reading area or area for film projections. On the second floor is the reading room and documentation consultation area, accessed by the public upon accreditation at reception. On the remaining floors above ground are the administration areas, laboratories, and documentation processing areas. These are all non-public use areas. Below ground, and also for private use, are the document vaults, meeting rooms and parking facilities. These spaces are accessed directly from the street level by a car lift. The main façade has been designed as a vibrating glass front that increases the perception of the building, breaking with the flatness of the street and emphasizing its location. The design seeks great transparency, allowing the workings of the building and the structure to be understood from the exterior. The outer glass skin is printed with extracts of texts from some of the documents preserved within the archive, in such a way that the building is not seen as sealed place, private and closed off from the citizen. The interior façade has been designed with a language that tries to establish a formal dialogue with the rest of the buildings of the block, while retaining the contemporary character of the building. This façade and garden seeks to project a friendly image to the users of the courtyard, dignifying a typology normally uncared for in the buildings of the Ensanche. In the interior of the building, we have opted for double height ceilings, with visible crossing points that will enrich the relationship between the different uses existing in the building. The planned work areas are clear, free of columns and flexible in order to facilitate adaptability to possible functional changes. As much of the program has been developed underground, the use of natural light and ventilation has been maximized, in such a way that the lobbies to access the document vaults or garage, which is 20 metres below ground level, have natural light and ventilation. The nucleus of vertical communications and the nucleus of the lavatories of the building above ground level also have natural light. As a result, most of the spaces and areas of circulation are bright and pleasant.