Ancient city grew from outside in

Roughly 6,000 years ago, Mesopotamian cities in what's now southern Iraq began as central clusters of buildings and then spread as orchestrated by authorities. About the same time, a different pattern of city development occurred in northern Mesopotamia, a new investigation finds. Instead of expanding outward from a densely populated core, an ancient metropolis in what's now northeastern Syria emerged over an 800-year period as a number of settlements grew together and expanded inward toward what then became the city's core, say Jason A. Ur of Harvard University and his colleagues.