The construction of cities was the end product of trends which began in the Neolithic Revolution. The growth of the city was partly planned and partly organic. Planning is evident in the walls, high temple district, main canal with harbor, and main street. The finer structure of residential and commercial spaces is the reaction of economic forces to the spatial limits imposed by the planned areas resulting in an irregular design with regular features. Because the Sumerians recorded real estate transactions it is possible to reconstruct much of the urban growth pattern, density, property value, and other metrics from cuneiform text sources.