Watch | The largest rooftop greenhouse of Chicago

A New York company called Gotham Greens has built what its owners claim is the largest rooftop greenhouse in the world in Chicago. The massive greenhouse is 75,000-square-feet and rests atop a soap factory. The company already has three smaller rooftop greenhouses in New York City- two in Brooklyn and another in Queens. It provides fresh lettuce and other greens for neighbouring stores and restaurants. The company's co-founders plan to continue to expand their facilities and develop a niche market with restaurants and grocery stores that want the freshest perishable greens.