The world's largest green roof: Developers unveil plans for sprawling $3bn project in Silicon Valley containing residential apartments, offices, parks, running trails and wildlife sanctuary

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Developers have announced ambitious plans to build the world's largest green roof - featuring sprawling green fields, apartments, offices and four miles of running trails - on a neglected shopping mall in the heart of Silicon Valley.

If approval for the $3billion project is received, the green space would measure a total of 30 acres and feature artificially-created running trails, vineyards and orchards.

Other elements to be found on the site include an amphitheater, children's play area and a refuge for native species of animals and birds.

Pictured is an artist's impression of what would be the world's largest green roof, in Silicon Valley, would look like if local authorities approve it

From ground level, the massive creation would sprawl across city blocks and include bridges to allow pedestrians to pass from roof-to-roof

The 30 acre green space would contain shops, parks, running trails and a wildlife sanctuary in the middle of suburban Silicon Valley

The green roof is just one element of the proposals, which would also see nearly 1,000 apartments and 100 square meters of office space also built, on Vallco Shopping Mall, located in suburban Silicon Valley near where the new Apple campus is being built.

Currently half empty, the mall has continued to decrease in popularity since the 2008 recession.

Sand Hill, the developers behind the proposals, argue that shopping malls have been a dying model for a number of years and this plan is a positive step toward reviving the area.

Reed Moulds, the company's managing director, said: 'The overall design integrates seamlessly into the surrounding community. It was very important to us that resident and business feedback shape the design for The Hills at Vallco.

'One item at the top of many people's wish list is a true town centre for Cupertino.'

If approved, the complex will feature its own street grid system, helping individuals move around the many stores and restaurants.

The Hills at Vallco, as the project is known, will target the highest certification in the green building standards through the use of recycled water for irrigation, heating, and cooling systems, and recapture rainwater to reduce water consumption.

However, the designs will not be approved by the City of Cupertino until at least 2016, the company said.

Remarkably, the wide expanse of green space - all built on the roofs of existing buildings - would feature running trails and wildlife reserves

Ambitious developers even hope to install a vineyard (illustrated) above the shopping mall and nearby office roofs

Mr Moulds added: 'The Hills at Vallco will completely transform the outdated Vallco Shopping Mall into a mixed use town centre and the heart of the City's emerging downtown.

'The unprecedented 30-acre community park and nature preserve will not only be the largest community park in Cupertino, but also the largest green roof in the world.

'This would be a unique mixed-use town centre with an authentic sense of place, connection, innovation and beauty, and a level of vibrancy and sustainability not yet experienced in Silicon Valley.

'We look forward to continuing our partnership with the community and the City to create a vibrant and sustainable neighbourhood where people can shop, dine, live, work, learn and play.'

Developers say it would be the 'largest community park in Cupertino [Silicon Valley] but also the largest green roof in the world'