(Click to Enlarge) Urban density is influenced by everything from topographical limitations to infrastructure. While high density is more often associated with poverty and overcrowding, Urban Age has found that it can also create a higher quality of life. In high density areas, the environmental impact of a city is lessened as walking and cycling become viable means of transportation; higher density can also inject vitality into urban areas and allow for the provision of public transport and various other amenities. Above, the urban density of several Urban Age cities is illustrated in terms of the number of people living in each square kilometer of a 100 x 100 km urban area. (Clockwise from upper left, cities illustrated are Johannesburg, Berlin, São Paulo, Mumbai, Shanghai, New York and Mexico City.) Courtesy of Urban Age, London School of Economics