Agonalis Obelisk (atop Bernini's Fountain)

A Roman-made obelisk with meaningless hieroglyphs — the craftsmen couldn't read Egyptian and carved several symbols upside down. Originally for Domitian's Temple of Serapis; now the centrepiece of Bernini's Fountain of the Four Rivers. The combination of fake-Egyptian ancient stone and supreme Baroque sculpture is one of Rome's great artistic ironies.