Historian Michael Wood travels to six regions where cities first rose from hunter-gatherer life, tracing how civilization itself began. The series opens on the Euphrates in southern Iraq, where the first cities appeared roughly 5,000 years ago and gave rise to Mesopotamian centers like Ur and Babylon, then moves on to India, China, Egypt, Central America, and Western Europe across six episodes. Wood walks the actual sites, from riverbanks to excavated ruins, using each location to ask what made settled city life take hold there and what it cost the people who built it. Rather than a single origin story, the series treats civilization as something that happened independently in different places for different reasons, tied to rivers, agriculture, and the organization of labor. The through-line is a question Wood keeps returning to at each stop: why did people trade the freedom of hunting and gathering for the walls, hierarchies, and record-keeping of city life, and what does that choice still shape today.