Sure bet: corporate HQ for a high-tech firm is an internal city within a vast shed with streets, open spaces and free-standing pavilions, their design essays in material experiment.

YouBet.com is an American Internet horse-racing service, giving instant access to live races, information about them and betting on them. It is America's first such service and its existence opens up interesting possibilities for inhabitants of those states where gambling is forbidden. The enterprise is Californian and in settling itself in new corporate offices in San Fernando Valley, it called on the services of two youthful Californian practices, Lorcan O'Herlihy (Lorcan O'Herlihy Architects) and Larry Scarpa(Pugh + Scarpa Architects), who joined together for the purpose.

It is plain that the two architects enjoyed their collaboration. In their different ways, both have drawn on the traditions of Californian Modernism, for they have a shared preoccupation with lightness, material experiment and texture. In design of Californian houses, O'Herlihy has shown a talent for composition and for manipulating space and light (Ars October 1996 and February 2001). Pugh + Scarpa's experience of exploring the potential -- both functional and sculptural -- of cheap materials, such as corrugated steel sheeting and concrete blocks (AR March 2Q01) has been put to use in this scheme.

YouBet's new headquarters, once those of Xerox, is an enormous shed measuring 3250 [m.sup.2] (3500sq ft) and 4.9m (16ft) high on a business park. The company's old offices had been depressingly anonymous and commercial, and staff wanted premises that would not only serve requirements for secure offices, board and meeting rooms and public space, but would be a source of pleasure and humour for 190 employees, some of whom would be inevitably tied to computer screens.

The building was stripped back to the essential shell, revealing a wooden ceiling of joists and laminated boarding, thin columns and a bare concrete floor which, with all its defects, was simply sealed and polished. Within it, the architects devised a plan modelled on that of the medieval city. The main axis of the building runs north-south and at the core there is a self-contained and densely equipped service centre, consisting of the racing and network operations, and research labs.

Around the core, like a protective belt, the architects threw a series of zones for the different divisions of the company. They are secured by checkpoints requiring pass cards and are functionally and visually connected to the core by elegant silver ducting carrying the various services. To the south is a big public space with a cafe, and around the perimeter are daylit offices. Skylights cut into the roof wash the middle reaches of the deep plan with luminance.

Ultimately this scheme has to do with the architects' pleasure in materials and light, and in juxtaposition of the rough and refined. Translucent panels contain open workstations, and the data centre is enclosed by long acrylic panels, curved in cross-section and set horizontally. Illuminated from behind, these panels form glowing corrugated walls. Corridors threading between these gauzy divisions open out in places into piazzas' with free-standing pavilions like pieces of sculpture. The main pavilion next to the cafeteria is a pure diaphanous glass box fitted with sliding panels so that the room can be opened up or closed for the company's most important gatherings; others are organically shaped, with a curving translucent skin, or composed of rough grey stucco held by an open cage of steel reinforcing bars.