Crystal pavilions: two luminous pavilions make a fine addition to a traditional European square.

The two little pavilions in Bologna's historic main piazza have recently been discussed in these pages (AR October pp38-39), so they do not need to be described at length here. They form the entrance to subterranean exhibition galleries that show the municipality's latest projects. (The galleries themselves are made by converting an existing but abandoned underground shopping centre.) One of the pavilions houses an introductory display, and the other has a reception desk and the head of the stairs down to the main exhibition.

Their outer cladding is of curved full-height laminated glass panels with silicone joints. The inner skin is made of 120mm diameter Plexiglas tubes that touch each other, like a sophisticated vertical version of Frank Lloyd Wright's glazing at Johnson Wax. Between the two is a 250mm wide cavity that is heated by warm air blown in from below to prevent condensation and to heat the spaces. Ducts that deliver the air are concealed under the raised floors, which are expressed outside as plinths that make the glass walls seem to be hovering over the cobbled surface of the piazza.

Lightweight roofs are supported on hollow circular steel columns so, seen from outside, the pavilions appear to be supported entirely on their translucent walls. These change according to the weather and time of day. In sunshine, the tubes reflect light and the pavilions seem to shimmer against the surrounding old buildings. At night, coloured LEDs (light emitting diodes) at the bases of the tubes transform the pavilions into large luminous sculptures.

The jury commended the boldness yet delicacy of the light-filled oval structures, which in no way detract from their fine setting, but gently add to the precious cityscape.

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