The nineteenth and twentieth centuries saw the
urbanization of cities.
Jacob Riis and other reformers fought for parks in urban areas. While many societies had traditions of intense urban plantings, such as the rooftops of pre-conquistador
Mexico City, these traditions did not reemerge on a larger scale in the industrialized world until the creation of naturalistic urban parks, such as the ones by
Calvert Vaux and
Frederick Law Olmsted. More recently, groups such as
squatters and
Reclaim The Streets have performed
guerrilla plantings, worked in and on abandoned buildings, and torn holes in highway asphalt to fill with soil and flowers. These actions have been effective in creating new planted zones in economically stagnant areas like urban Eastern
Germany, where abandoned buildings have been reverted to forest-like conditions. ==See also==