21st Century Museum of Contemporary Art, Kanazawa

Kanazawa already had a formal provincial art museum, so the brief for this one asked for its opposite: a museum people would walk into without deciding to. Sejima and Nishizawa answered with a circle. There is no front and no back, no steps, no plinth; four entrances face four different streets, and the glass wall that closes the plan carries no visible frame, so from the lawn the building reads as a low disc of light with white boxes floating over it. Inside, the curators had asked for ideal rooms — square, rectangular, round, of many sizes — and SANAA scattered them across the disc as separate volumes with corridors and courtyards left over between, which is what makes the route ambiguous and the visit unrepeatable. Construction ran from April 2002 to August 2004; the museum opened that October and SANAA took the Golden Lion at Venice.