A prehistoric megastructure, Seahenge, emerges from the sands of an English shore in the county of Norfolk that could reveal lost mysteries of the Bronze Age, 4000 years ago; using pioneering technology and 3-D imaging analysis, experts investigate and uncover dark, ancient rituals once performed here.

The secrets of the world's oldest sunken city, Pavlopetri off southern Laconia in Peloponnese, Greece, are lost to history, but hi-tech underwater archaeology answers questions that books cannot; experts explore sunken ruins and reveal new discoveries about one of the first great empires.