Beyond the galleries, the Snohetta’s interior attractions are many: a multipurpose performance space, two restaurants and a spacious third floor reserved almost entirely for the museum’s exemplary photography collection (with a coffee bar in its midst), and terraces for viewing sculpture. Amphitheater seating overlooks the new Howard Street entrance, whose lobby holds, just barely, an enormous spiraling sculpture by Mr. Serra that is part of the Fisher Collection.

Image The new building’s rippling, sloping facade. Credit... Henrik Kam/SFMOMA

The facade is supposedly inspired by the waters and mists of San Francisco Bay, but its associations are free-range, variously artificial and natural. It conjures an iceberg, a pueblo and an exceptional cruise ship, but also seems pleated, hand-carved and digital. (It could also be an enormous cloth Anachrome painting by Piero Manzoni.) The exterior stimulates sight, mind and imagination, readying you for the unpredictable pleasures and demands inside.

Once you’re there, this subtle flexing of the senses continues, stimulated not just by the art but also by the continual surprises of the building’s design and details. Nothing really repeats, exactly, most excitingly in the broad corridors along the building’s east facade, where staircases alternate with big windows. These offer panoramic views, while their thick frames echo the light wood flooring and provide wonderfully deep window seats. The interplay of geometry, material, light, space and angle of view relates to installation art and is one of the building’s hallmarks.

The main flaw of the Snohetta building may be that the San Francisco Modern’s 1995 structure was not demolished to make way for it. In a feeble attempt at unification, Snohetta replaced the original black granite staircase with a wider one in light wood, but the Third Street lobby retains its black floor and its ridiculous full-height atrium. Outside, the symmetrical Botta building now sits before its larger, softer-looking sibling like a pharaonic gate.

Still, the Botta building offers exceptional galleries, now refurbished, and Snohetta took care to knit the levels inside the structures almost seamlessly.