Sustainable Cities for Smart Urban Growth
Once upon a time, there was a place with good soil for plants and good sources of water for wild animals. Many, many plants grew there, and many wild animals made it their home. People liked it too. In fact, so many people wanted it to be their home, they built a city. The world's big cities -that are now full of skyscrapers and wide concrete avenues, and where the only wild animals live in zoos- once looked very different. Many were farms. A few were jungles or swamps. A handful were desert oases. Even today, cities cannot be separated from the natural environment. Natural ecosystems provide the resources that cities need to develop and grow, including water, clean air, soil, food, and energy.