Urban social geography
Urban social geography is a sub-field within human geography, looking at the factors within an urban environment that affect human relationships on social, economic and political levels. Those human relationships then feed back into the factors which then shape dynamics of the actual city itself. With numerous inputs and outputs, this study is a constantly evolving field. Cities are more than just a dot on the map or a set of buildings. Alcaeus, a Greek poet, wrote about cities "not the house finely roofed or the stones of walls well builded, nay, nor canals, and dockyards  make the city, but men able to use their opportunity". Cities have also been described as prisms in which one can see the social, economic, and geographical characteristics from which they evolved. Urban centers not only have a disproportionate percentage of the population, but also have a large amount of fixed assets, capital, labor resources, and productive capacity. Key individuals. Significant figures in the study of urban social geography include Manuel Castells, David Harvey, Doreen Massey and Nigel Thrift.