This former apartment building in Colonia Cuahtemoc, off the Paseo de la Reforma, is now occupied by offices, a common transformation in this area of Mexico City. The building was designed and built in the 1930s by a Swiss engineer as a classic International Style concrete frame structure adapted to the benign local climate. As a result of incremental alterations carried out over the years, the building has become a run-down hodge-podge: the balconies, envisioned as hanging gardens, now face a bustling commercial street; the courtyard is littered with debris and construction supplies; the-now necessary security barriers are off-putting to occupants, visitors and passers-by alike.

The goal of the project is to transform and "rejuvenate" the building, making it more functional and appealing to both current and future occupants. Our fundamental approach is based on exploiting the advantages of the climate and the existing building framework by blurring the boundary between interior and exterior. At the same time, the impact on the building of such present-day Mexico City realities as pollution, noise and security problems is recognized and addressed through solutions integral to the design.

Facade: A new glass screen is "floated" just off the leading edge of the existing balconies, creating a translucent veil that lets in natural light and air, permits visibility from the interior, and yet protects the privacy of the building occupants. This is achieved through application of a graduated dot pattern to the glass, which creates an abstract cloud-like effect. The ends of the balconies are left open, allowing for ventilation and for oblique views of the street. The balconies become small gardens filled with potted plants. Large clear-glass sliding doors set in the existing exterior wall can be opened during working hours to enhance the sense of spatial expansion of the interior.

Courtyard: The court, which provides natural light and ventilation to the interior offices, is lined on three sides with a living green "screen" of vines. This transforms the court into a walled garden, while offering a certain amount of privacy to the offices overlooking it. On all floors, the existing elevator lobbies are extended to the edge of former exterior stair landings in order to accommodate reception areas and create a sense of arrival. The elevator lobby wall - the fourth wall of the courtyard - is made of frameless glass panels that can be folded back, opening up onto balconies planted with aromatic flowers. Existing water cistern in the court is submerged below grade and the collected rainwater is used to nourish the new green wall. A small fountain refreshes the air and provides a soothing sound mask for the surrounding offices.

Ground Level: Storefronts in each of the three street facade bays are replaced with new frameless glazing. The security room is relocated into the core in order to create a more spacious, uncluttered lobby and establish a visual corridor from the lobby entrance to the inner court. At the courtyard side of the lobby, the fire escape is relocated and the lobby wall replaced with frameless glass panels that, when folded open, allow the lobby space to flow seamlessly into the court.

Penthouse: A new rooftop addition at the street side is designed as the executive suite, with a reception area, conference room, bar/lounge, private office and bath. Large sliding glass doors at the perimeter open out onto landscaped terrace that wraps around the suite. The penthouse roof, a thin flat cantilevered concrete plane, extends to the edge of the building at the front and sides. Providing shade and protection from the elements at the penthouse level, it also acts as a compositional counterpoint to the plane of the glass facade and as a visual boundary between the building and the sky. The underside of the roof is painted a light cerulean blue, enhancing the sensation of "floating ".