While the extent and complexity of the programme prompted the construction of more than one volume, the terms of the area planning guidelines allowed 100% occupation of the site, with a height limit which suggested a single compact building. This apparent contradiction was resolved by the design of a great “container” which houses in its interior the pavilions with their different functions, like an architecture inside an architecture. The seven and a half-metre geometrical grid modulates the side into autonomous units, recreating an urban structure of streets and squares in its interior. The building is divided internally into four blocks. The least regular of these contains the catering services and stores. The two linear blocks which frame the central space are given over to offices and meetings rooms. The conference hall, which occupies a central position, is bounded by four vertical communications towers, and projects its triangular from beyond the glass skin of the façade. The roof of the main hall has been made accessible, serving a variety of different functions and taking the form of an elevated central square within the urban layout of the building’s interior. Program: two auditoriums with a capacity for 2,000 and 1,500 people respectively, offices, exhibition hall, cafeteria, restaurant, banqueting hall, and car park. Client: Campo de las naciones s.a. Gross area 72,000 m2