We visit farmers growing lettuce, herbs and strawberries indoors in the middle of cities. The plants are stacked up on shelves in vertical farms that use hydroponics and aeroponics to cultivate them. The idea is to grow food closer to where it’s eaten. At the moment, cities get most of their produce delivered from far away, but transporting it uses energy, while fruit and veg can lose their freshness in transit. We visit two European companies hoping to change the supply chain. One makes indoor farming units for food retailers, restaurants and hotels, and the other grows strawberries in shipping containers on the outskirts of Paris. We find out if these pioneers of European urban farming are able to feed our growing cities. Produced and presented by Dina Newman. Picture credit: Getty Images