How can we in an urban context reconcile design with evolution? Designers are generally educated to offer a certain, controlled view of the world, seeking definite solutions, whereas the city tends to represent collective human life and be unharnessed in its growth and contractions. Throughout history, human habitats have largely been the consequence of organic growth – the layering of many hands – rather than the result of a single grand design. But in today’s worldwide climate of accelerated urbanisation, the need for architects and designers to engage with the city in flux is more compelling than ever. Cities with their urban populations are accreting and evolving in the developing world with a super–charged energy and diversity all of their own. The speed and complexity of current change is not just unsurpassed for our species, but unprecedented in life on earth. Meanwhile, long–established cities in the developed world continue to need to adapt in order to remain liveable for their own ever–growing populations. Here Sir Terry Farrell, who has built an international career as an architect–planner, encourages other planners and architects to follow the biologists – look at, learn from and indeed admire the nature of the forces that drive the change, and then with humility and respect work with them to nudge, anticipate and prepare for where it takes us. Searching for patterns within the apparent turbulence and complexity, he analyses the notions of urban design and urban evolution and examines whether or not they need necessarily be seen as opposing one another. The first two chapters discuss emergence as an idea in a biological and architectural context, as well as the distinction between urban design and planning in both education and practice, and the impact of other fields such as landscape design. Seven further chapters examine a range of themes embracing the importance of chain reactions in the progress of urban engineering; the character of habitation; layering; taste and context; adaptation and conversion; the advocacy of the architect–planner; and the effects of digital technology on city evolution. Farrell brings his considerable experience in practice to bear, elucidating his thoughts with examples from cities across the world, including Beijing, Hong Kong, London, New York and Paris.