Images of the Parthenon as a stark, white structure set against an azure sky will have to change. Researchers have found the first evidence of coloured paints covering its elaborate sculptures.
The temple, which tops the Acropolis in Athens, Greece, dates from the 5th century BC. Its carved statues and friezes show scenes from Greek mythology and are some of the most impressive sculptures to survive from ancient Greece.
Pigments are known to have adorned other Greek statues and temples, but despite 200 years of searching, archaeologists had found no trace of them on the Parthenon's sculptures.
So Giovanni Verri, a researcher at the British Museum in London, developed an imaging technique that is ultra-sensitive to traces of an ancient pigment called Egyptian blue.
Verri shines red light onto the marble, and any traces of paint that remain absorb the red light and emit infrared light. Viewed through an infrared camera, any parts of the marble that were once blue appear to glow.
Egyptian blue has shown up on the belt of Iris, Poseidon's messenger goddess (see image), and as a wave pattern along the back of Helios, god of the sun, who is shown rising out of the sea at dawn. It also appears as stripes on the woven mantle draped over another goddess, Dione (see image).
"This adds another dimension to how we perceive the Parthenon," says Ian Jenkins, also at the British Museum. He says the temple would originally have looked "jewelled" and "busy". The main pigments used are likely to have been blue and red, with the white stone showing through in parts, as well as gilding.
Jo Marchant has written more on the Parthenon mystery here