People aren't shopping much at the Vallco Shopping Mall in Silicon Valley, so they're turning it into a green, walkable neighborhood. Vallco Shopping Mall, in the heart of suburban Silicon Valley, is a classic example of the dying shopping center. Half the stores are empty, the food court is abandoned. So now developers plan to start over. The mall and the sprawling adjacent parking lot may be turned into a new walkable neighborhood, topped with the largest green roof in the world.

"It's not easy to be a shopping mall these days," says Reed Moulds, managing director at Sand Hill, the developer behind the $3 billion redesign. "We've done some research and we haven't found a single shopping mall that's started construction since 2006. This is clearly a dying model. That's on display at Vallco." After months of community meetings, the developers realized they had to take a completely different approach to the mall—not just knock it down and add new stores. The new design, if it's approved by the city of Cupertino in 2016, will have a downtown-like street grid with town squares for farmers markets, and will be lined with stores, offices, and hundreds of apartments. All of this will be wrapped inside a 30-acre park with running trails, vineyards, orchards, and gardens. "For us, the challenge was how do we bring to the community the town center they've wanted for decades, revitalize retail at this location, but also meet their desire for a model for sustainable growth and a desire for open space," Moulds says. "The 30-acre community park and nature reserve was what they've always wanted."