A 10,000-year transect of Roman populations Rome wasn't built (or settled) in a day. Antonio et al. performed an ancestral DNA analysis to investigate the genetic changes that occurred in Rome and central Italy from the Mesolithic into modern times. By examining 127 Roman genomes and their archaeological context, the authors demonstrate a major ancestry shift in the Neolithic between hunter gatherers and farmers. A second ancestry shift is observed in the Bronze Age, likely coinciding with trade and an increased movement of populations. Genetic changes track the historical changes occurring in Rome and reflect gene flow from across the Mediterranean, Europe, and North Africa over time. Science , this issue p. 708