The green cities are not only buildings with balcony full of flower or plants or walls full of vines, something like the Hanging Gardens of Babylon, 21st century version. Neither are cities only with beautiful parks, as they make think the images that accompany this text. What we call the green city is a concept to get as close as possible to the definition of sustainable development, thought towards the end of the 20th century, which emphasizes the reconciliation between economic well-being, natural resources and society.
The green cities are being built considering clean energy such as wind and solar, waste management, sustainable transport such as electric cars, green spaces for recreation, bicycle paths, areas for sport and culture, for the enjoyment of its inhabitants. Special emphasis is placed on the management and efficient use of natural resources such as drinking water, electricity and the recycling of wastewater.