Did Alexander the Great really build sixteen cities in Afghanistan, or was he the destroyer of a far more ancient civilization? David Adams goes in search of the most alluring of them all - Alexandria on the Oxus. And it appears to be the other way round - Alexander discovered a highly developed civilization - a lost world - that pre-dated even the Persians. As Adams unravels the mysteries of the Oxus Civilizations, its great fortress cities are dramatically recreated in stunning CGI.