The clifftop ruins of Tintagel Castle in Cornwall, England are shrouded in a tumultuous history and believed to be the birthplace of King Arthur; experts use cutting-edge tech to unlock the secrets of this ancient structure and reveal the truth behind a legendary ruler. 

Behind the presidential faces of Mount Rushmore lies concealed secrets and the Statue of Liberty contains a dark, enigmatic history; experts use the latest science and technology to investigate and reveal undiscovered mysteries of American monuments. This is a mashup of S03E04 "Statue of Liberty: The New Secrets" and S06E04 "Mount Rushmore: The Hidden Secrets."