The 21st century will be the age of the city. Already over 50% of the world population live in urban centres and over the coming decades this percentage will increase. Blending anecdote, fact and first hand encounters - from exploring the slums of Mumbai, to visiting roof-top farms in Brooklyn and attending secret dinner parties in Paris, to riding the bus in Latin America - Leo Hollis reveals that we have misunderstood how cities work for too long. Upending long-held assumptions and challenging accepted wisdom, he explores: why cities can never be rational, organised places; how we can walk in a crowd without bumping into people, and if we can design places that make people want to kiss; whether we have the right solution to the problem of the slums; how ants, slime mould and traffic jams can make us rethink congestion. And above all, the unexpected reasons why living in the city can make us fitter, richer, smarter, greener, more creative - and, perhaps, even happier. Cities Are Good for You introduces dreamers, planners, revolutionaries, writers, scientists, architects, slum-dwellers and emperors. It is shaped by the idea that cities are the greatest social experiment in human history, built for people, and by the people.