Food and shelter
Growing baby vegetables hydroponically is the new use for tunnels in London, idle since they were used as underground air-raid shelters in World War Two.
Once intended for extensions of the London Underground, the tunnels protected up to 8,000 people from bombs. They were abandoned for 70 years, until entrepreneurs Steven Dring and Richard Ballard decided to turn them into an urban farm, producing the edible cotyledon growth stage (sometimes known as microgreens) of broccoli, coriander, fennel, and other herbs. The crops are grown 33 metres (108 feet) below street level in nutrient solutions, instead of soil.
This hydroponic technique can also be used for growing tomatoes and peppers.