The building is located in the center of Madrid, slightly to the south. Only a few minutes walking from Atocha Train Station, El Retiro and Madrid Río parks, the so called Paseo del Arte (Reina Sofía, Prado and Thyssen-Bornemisza museums) and Caixa Forum and Matadero cultural centers. It is a consolidated area of the city that is being transformed, starting to renovate its old residential, industrial and commercial buildings linked with the railways. All this confers a new hybrid and cosmopolitan role to this fragment of the city, vibrant, full of life and activity. It is a plot between party walls, long and narrow, with south orientation, that was occupied in the past by a building from the beginning of the XXth century. Its bad condition suggested the demolition. In the access, a lattice unifies the whole front of the building towards the street and defines a veiled hallway that articulates the three main programs: housing entrance hall, parking and office. The structure is shifted to the party walls and disappears. Each floor is occupied by a single programmatic unit, materializing the idea of living in an elevated house located in the center of the city. At the top, a two-storey house inverting the traditional spatial organization, takes advantage of the setback imposed by local regulations to use it as a terrace. The facade works as an energetic diaphragm defined by different layers that occupy the whole front. From the exterior limit in the street to the interior of the enclosure, these layers made of complementary materials are unfolded to control ligth, ventilation, privacy and landscape. The influence of the existing surroundings is materialized in this building placing a particular emphasis on the party walls, orientation and street performance, making that the building response emerges as the intensification of the urban condition and not as a mere insertion of a volume in a gap.