Casa Vieira de Castro perches halfway up at the southwestern end of a hill that overlooks the town of Vila Nova de Famalicao in Portugal. Previously intended as a sanatorium, the site has since been acquired by a local industrialist, who commissioned architect Alvaro Siza into developing it. The site now consists of a caretaker’s house, a two-storey family house and a swimming pool with a terraced garden. Recalling the traditional quinta, the Casa Vieira de Castro brims full of personal and regional identity, an architectural design that is truly trademark Siza.

Design of a house in northern Portugal makes use of existing groundworks on a site overlooking the local town.

Casa Vieira de Castro, by Alvaro Siza Arquitecto, is at the southwestern end of a terrace built halfway up the precipitous slope of a hill. It overlooks the industrial town of Vila Nova de Famalicao in northern Portugal, which lies about 18km south-west of Braga and has a history of watchmaking. The terrain is rocky and, with a relatively high rainfall in this part of the country, green with pine and oak. From this vantage there are southerly views over an immense landscape; conversely from the valley, the house can be seen from far away, an abstract form etched sharp and white against the forest.

The site, with an old house at the north-eastern end, had been destined for a sanatorium. When acquired by the client, who is a local industrialist, it contained only the foundations and plinth of the unbuilt sanatorium and a wide flight of shallow stone steps.

Development of the site was in three phases. The first task was to restore the old building, and convert it into a caretaker’s house. The second phase provided a two-storey family house for the client, built upon the existing plinth. The third, still to be completed, consists of constructing a swimming pool and creating a terraced garden out of land cleared of forest. Formal entrance to the estate is from the east, where you pass the caretaker’s house before ascending the steps. Service access and garaging is on the west.

In general the Portuguese have a strong sense of their own culture. For Siza the house is a repository of personal and regional identity, and bastion against the forces that try to render the world more uniform and impersonal.(1) Though couched in abstract form, the architecture of this house, like Siza’s other works, acknowledges tradition. The essential dignity of the building, deriving from proportion, composition and massing of its parts, and the way it is visibly set apart on the hillside, with a commanding view of the town, recalls the traditional quinta.

But it is the physical nature of the place with its stupendous prospect that is plainly at the heart of the design. The back of the house gives onto the sheltering belt of trees while the south is faceted and at almost every turn the interior is open to the landscape.

Seen from the west, the sequence of stepped and cut out volumes look to be carved from a single solid. This is partly because of the constant height of the building and uniformly white walls, and partly because the openings are relatively modest - as they are in traditional Portuguese houses. So white planes dominate. Approached from the east, where cut-outs are larger and volumes interleaved, the house has a less solid appearance. Projections and indentations of the plan at upper and lower levels have produced a fragment of a colonnade on the ground floor and first floor terraces like eyries.

Inside the kinetic envelope, the interior is conventionally and very comfortably arranged with the living quarters on the ground floor and four bedrooms above. Each of these has a bathroom and gives onto a terrace. Siza is in the process of designing the furniture throughout the house.

The further you get from the moderating influence of the Atlantic, the more severe the winters, and open fires are traditionally common in the region. On the ground floor, the massive form of a fireplace, handsomely lined with white marble and an architectural element in its own right, creates separation between double-height hall and dining room. and between hall and living room (for otherwise the spaces simply flow into one another).

The living room, which strikes you as a vessel of light, stretches eastwards from the fireplace towards the pool. It is illuminated along its considerable south-facing length by a narrow strip of sliding windows, the south light partly diffused by the colonnade. At the eastern end, big glass panels, set at a slight angle to the pool, allow you to look down the length of the terrace.

Finishes and materials are spartan: white walls hover above gleaming oak floors, with pale Portuguese marble being used for bathroom and kitchen floors and on walls. Internally, doors and window frames, simply designed, are wooden; externally openings are framed in painted metal or wood with door and window cills in marble. But the manner in which light and shadow have been treated as an almost tangible component of the architecture transforms mere austerity, giving edge and surface to form, and imbuing this house with a sense of spiritual enlightenment.