Public parks are many things to many people: a space devoid of domestic chores and patriarchal expectations, a spot to cultivate friendship or love, a place where you can experience a feeling of freedom that is absent elsewhere, an opportunity to «visit» trees from a country you have not seen in a long time, a way of being part of a group while sitting alone on your bench - or even the perfect setting for running a small business to help you get by. Public parks are all this and much more if we're to believe the inhabitants of four Asian mega-cities - Chennai, Singapore, Manila and Shanghai - who were interviewed as part of a recently-published study. Green spaces, we learn, do much more than simply benefit biodiversity and health: they also meet numerous other essential human needs that open the door to sustainable well-being, a concept based on a combination of personal well-being and the necessities of sustainable development.