A head-turning new landmark has taken shape in downtown Los Angeles. On Grand Avenue, opposite Frank Gehry’s shimmering Walt Disney Concert Hall, construction is almost complete on the Broad, the much-anticipated contemporary art museum founded by mega-collectors Edythe and Eli Broad. Opening September 20, the Diller Scofidio + Renfro–designed building will be home to the couple’s trove of nearly 2,000 treasures, among them seminal works by Cindy Sherman, Christopher Wool, and Jordan Wolfson. The firm conceived the three-story, 120,000-square-foot structure as a combined “vault” and “veil.” The former refers to the core of offices and storage on the second level, which visitors pass through on the way from the lobby to the column-free exhibition space on the top floor. The veil, meanwhile, is the meshlike exoskeleton of 2,500 fiberglass-reinforced concrete panels that wrap the entire edifice, with angled perforations channeling indirect natural light to the interiors. The museum’s big debut may still be months away, but this spectacular structure is already stopping traffic.