Nero's bathtub

Nero's 25-foot-diameter bathtub, better described as a porphyry basin, was commissioned by Nero between 54-68 AD for his Domus Aurea (Golden House). It was carved from a single, rare slab of Imperial porphyry from Egypt.

Imperial Porphyry is a prized, deep purple, volcanic igneous rock with white feldspar crystals, quarried exclusively by the Romans in ancient Egypt at Mons Porphyrites (now Jabal Dokhan). At the center of the Pantheon in Rome is a large circle of Imperial porphyry on the floor where, for 300 years, new emperors stood to be crowned.

Its immense value comes from the rarity of the purple porphyry and its historical connection to Roman imperial power. The quarry is now depleted, making the artifact irreplaceable. It is now located in the Pio Clementino Museum at the Vatican Museums in Rome.