You don’t usually think of taking the elevator up to the roof to enjoy your lunch in the park, but that’s exactly what shoppers in Cupertino are going to be able to do once the world’s largest green rooftop is built there.The Hills at Vallco is a huge green-roofed building project planned for the downtown heart of Cupertino, California. The 1.2-million-square-foot Vallco shopping mall, on 50 acres of land, struggled for years in a declining economy, until the Silicon Valley-based Sand Hill Real Estate company bought the land in 2014. Vallco’s new owners have plans to revive the dreary mall into a green and vibrant town center that will prioritize stewardship of the environment. The winning design for the space, by Uruguayan architect Rafael Viñoly and Olin Landscape Architects, includes plans for 800 apartments and 2 million square feet of mixed office and retail space across a grid of several easily-walkable city blocks.Green DesignThe area will be laid out with foot traffic in mind, and not cars. Instead of a concrete mall surrounded by acres of paved parking lots, gardens and running trails will weave through the neighborhood. The design for the new town center even includes plans for an orchard and a vineyard, both open to the public.But these parks and orchards won’t be on the ground. Instead of the traditional neighborhood parks, squares of green in a concrete grid, Viñoly’s plan is more lofty. Literally. An impressive 30 acres of gently rolling green space will connect the tops of many of the buildings in the complex, giving The Hills at Vallco what would be the world’s largest green roof to date, taking the title from Chicago’s 24.5-acre Millennium Gardens.The plans for the green roof include 3.8 miles of walking trails winding among the vineyards and orchards, which will be irrigated by a combination of recaptured rainwater and recycled water. The landscape design features several acres of native drought-resistant plants, which will provide a natural and familiar refuge for local wildlife while improving local air quality by absorbing excess CO2.