Tectonic transfer.

In the austere design of a museum, created within the walls of a palatial nineteenth-century building, the new impinges lightly upon the old.

The Pinacoteca do Estado houses the state of Sao Paulo's important collection of nineteenth- and twentieth-century Brazilian art. As a destination for visitors to the city it is as essential to see Mendes da Rocha's sober and graceful treatment of the palatial nineteenth-century building as to see the art it contains. The museum is at 141 Avenida Tiradentes, in the leafy bairro of Luz, north of the city centre. Now one of the seediest parts of Sao Paulo, its former affluence can be detected in the majestic Estacao da Luz and lushness of the neighbouring park.

The three-storey building was designed by Ramos de Azevedo and constructed of pale rosy brick. Apart from the handsome exterior with brick colonnades and verandahs across both short ends, its main features were a central octagonal courtyard and two flanking ones at ground floor level running across the long axis. It was originally intended to be the Liceu de Artes o Oficios (arts and crafts school) but even by 1905 the architect was converting some of it into a gallery for part of the state's collection.

The building's conversion into a large gallery required internal reorganization. As well as accommodating the permanent collection and its possible enlargement, the museum had to have space for temporary exhibitions and the environmental conditions demanded by modern curators.

To relate the museum to the public square, the Praca da Luz, to the south-west of the building and give it some breathing space, Mendes da Rocha moved the entrance away from the busy Avenida to this side. So the verandah, external but sheltered, becomes a welcoming transition between the square and ticket hall. The main axis, now running the length rather than the width of the building, is traced by two long corridors giving access to peripheral galleries and offices.

A roof of latticed glass over the three voids transformed them into luminous galleries. The ground floor of the central octagon is occupied by an auditorium, its roof forming the floor of the gallery from which you can see the length and breadth of the museum. Galleries on each side are lofty triple-height halls bridged at the upper levels by metal walkways.

This is an exhilarating building. Mendes da Rocha's clear plan, manipulation of light and evident pleasure in material and texture permit you to appreciate both the art and elegant sobriety of the setting. Part of the delight lies in his treatment of the brick structure which after cleaning and protection from humidity and pollution has been left to speak for itself. Window frames were removed from courtyard walls leaving simple openings, the marks of old scaffoldings, and other signs of previous occupations were preserved, as were the countless crumbling traces of refined ornamentation.