Agamemnon, hero of the Trojan War, apparently flew business class, flanked by two watchful handlers in adjoining seats.

Those in the know are mum on the details of how the Mask of Agamemnon—one of the best known treasures of ancient Greece—was conveyed to the National Geographic Museum in Washington, D.C., but they can confirm that the priceless gold artifact is now secure in its display case and ready to greet visitors when "The Greeks: Agamemnon to Alexander the Great" opens at its fourth and final venue on June 1, following earlier shows in Canada and Chicago.

The exhibition—the largest of its kind in a quarter century—has been as much a logistical triumph as a cultural one. More than 550 iconic objects