For hundreds of years, city planners have developed parks, planted trees and set aside open space in urban environments. Boston Common, a public square used for grazing livestock since 1634, was converted into a park in 1830. A quarter of a century later, New York’s Central Park opened, designed by Frederick Law Olmsted and Calvert Vaux. Olmsted, originally a journalist by trade, went on to develop parks throughout the United States, including in Wisconsin, Colorado, Washington, Georgia and the District of Columbia.The terms “urban greenery,” “green space” and “open space” all refer to urban design elements meant for recreation or improving a neighborhood’s aesthetic appeal — trees and other plants in parks, sidewalks or elsewhere; public plazas, schoolyards and playgrounds; and public lands covered with trees, shrubs and grass. Such projects can also function as “green infrastructure,” helping mitigate the urban heat island effect, filtering air and reducing runoff. A 2008 study of low-income Philadelphia neighborhoods even found that newly planted trees boosted sale prices of nearby houses by 2%.