An ever-greater proportion of humankind is living in cities. Open space and access to elements of nature—sunlight, fresh air, water, and plant life—are generally less available to urban residents than to those living in smaller communities outside large metropolitan areas. The denser a human settlement becomes, the greater the challenge for landscape architects, designers, and planners to provide people with suitable outdoor environments. The need for outdoor space in cities is evident in the popularity of parks and plazas. It has been observed that, in the case of well-designed urban outdoor spaces, supply creates demand. Parks and plazas that are thoughtfully planned and constructed tend to be used immediately. One only needs to watch city plazas and parks on warm, sunny days—filled with office workers taking lunch breaks outdoors—to witness this demand firsthand. High-density environments present a significant opportunity for landscape architects. Due to the abundance of buildings and structures, the total surface area of a city often exceeds that of the original landscape it replaced. These surfaces can be adapted to support plant life and provide functional outdoor spaces for people, turning the built environment into a canvas for urban greening and human-centered design.