Stefan Al, Dutch architect, urban designer, and educator, explores what makes trees a vital part of cities, and how urban spaces throughout history have embraced the inclusion of trees. By 2050, it is estimated that over 65 percent of the world’s population will be living in cities and the presence of trees will be one way to make these spaces more livable. While we may think of nature as being unconnected to our urban spaces, trees have always been an essential part of successful cities.