Norwegian architect Sn�hetta released its preliminary design for the 225,000-sq-ft expansion of the San Francisco Museum of Modern Art. General contractor Webcor Builders will face the challenge of a compact urban site, currently a maze of alleyways, that is 335 ft long but only 98 ft wide. The project includes a public promenade with an entrance to the wing, which will sit behind the Mario Botta-designed original that opened in 1995. A more detailed design, executed in partnership with the local EHDD Architecture, is scheduled for completion by the end of the year. Construction completion is set for 2016, though the museum has not announced a start-up date. Sn�hetta designed the Bibliotheca Alexandrina in Alexandria, Egypt, and the National Opera house in Oslo.