Great Zimbabwe is one of the most iconic sites in southern Africa and indeed the world, but like so many famous monuments it has suffered from the attention of early excavators who have destroyed key categories of evidence. Chronology is crucial to understanding the development of the various elements of Great Zimbabwe and its relationship to other important regional centres such as Mapungubwe. A number of radiocarbon dates are available, however, and in this study they have been combined with the limited stratigraphic information and with datable imports to provide a Bayesian chronology of the site and its structures. Construction of the stone walls probably began at the end of the twelfth or beginning of the thirteenth century AD, reaching its peak in the fourteenth and fifteenth centuries, although occupation continued up to at least the sixteenth and probably into the seventeenth century AD. These results indicate that occupation at Great Zimbabwe must have overlapped with that at Mapungubwe, and argue for a polycentric model of sociopolitical complexity in this region of southern Africa during that crucial formative period.