We all know about Alexandria, one of the greatest cities of the classical world, with its great Library and fabled Lighthouse. But Heracleion? A great port and religious centre at the mouth of the Nile, it was mentioned by the likes of Herodotus, but at some point it vanished, and its location became unknown.

Cast:Lucy Blue,

Genre:Documentary,

country:none

Production:STV Studios, BBC Studios Natural History Unit,