The below-ground space is accessed from the main entrance, where a staircase carved in pietra forte fiorentina, a material extracted from quarries in Tuscany and Emilia, leads to the exhibition space, consisting of three circular rooms and a large elliptical room. This space, which is in semi-darkness, is enveloped by 30,000 stone segments, each one individually designed and skilfully built and assembled so that they continuously envelop the entire space: a formal continuity that gives it a sense of unity and fluidity.
The choice of a single type of stone, pietra forte fiorentina, gives expression to a material that is extracted from deep quarries in Firenzuola. It gives the impression of a space that has been hollowed out: subtracted just as quarries are hollowed out to become works of architecture of unconscious beauty. Because of the size of each segment, which is 5 centimetres thick, one metre long, and is distanced 5 millimetres from its neighbours, the horizontal stripes of the stones give this imposing mass an effect of suspension that contrasts with the reflective specks from Mica flakes in the stone. They create a multitude of small points of light in the shadows and the solid mass.