The Domus Aurea, or Golden House, was the sprawling palace of the Roman emperor Nero. Archaeologists recently uncovered a chunk of Egyptian blue ingot, an example of the opulence of the palace itself.

In the ruins of Rome’s opulent Domus Aurea palace, archaeologists have uncovered an array of ancient pigments used by artisans to paint the walls of the emperor Nero’s stately marble home with ...