Its austere white is on every postcard, but the Athens Parthenon was originally daubed with red, blue and green, the Greek archaeologist supervising conservation work on the 2,400-year-old temple said.
"A recent cleaning operation by laser revealed traces of haematite (red), Egyptian blue and malachite-azurite (green-blue) on the sculptures of the western frieze," senior archaeologist Evi Papakonstantinou-Zioti told AFP.
While archaeologists had found traces of the first two colours elsewhere on the temple years ago, the malachite-azurite colouring was only revealed in the latest restoration process, Papakonstantinou-Zioti said.
Given the testimony of ancient writers, it is not unlikely that the Parthenon's trademark columns were also coloured, she added.
Archaeologists have been trying since 1987 to remedy damage wrought on the Parthenon's marble structure by centuries of weather exposure and decades of smog pollution.
Principal restoration work on the entire Acropolis citadel, which stands in the centre of the modern Greek capital, is scheduled to be completed by 2009.
Dedicated to the ancient Greek goddess Athena, patron of the ancient city of Athens, the Parthenon was badly damaged during a Venetian siege of occupying Ottoman Turkish forces in 1687.
Much of the temple's eastern frieze was removed in the early 19th century by agents of Lord Elgin, then British ambassador to the Ottoman Empire.
Elgin subsequently sold the sculptures to the British Museum in London, where they are still on display, despite persistent efforts by the Greek government to secure their return for the past 20 years.