Cities contain a remarkably diverse set of physical features, ranging from apartment buildings to factories, water treatment facilities to wildlife preserves, and alleyways to highways. Physical planners (including land-use planners, neighborhood planners, environmental planners, economic development planners, etc.) seek to guide the development of these features for the improvement of city life and livelihood. Often they do so through control or facilitation of private real estate investment. The purposes they strive for include residential well-being, environmental enhancement, enjoyment of public space, good transportation, economic prosperity, reduction of neighborhood distress, recreational opportunity, heritage preservation, public health and safety, and equity or cost-effectiveness in their achievement.