Despite their time on the monument (& the fact that for years, people have perceived them in their pure white form), traces of the original colouring  from the sculptures on the Parthenon are still visible.
Athens News Agency 
Traces of the Parthenon’s colourful past
(ANA-MPA) — An inset shows traces of mustard-coloured paint on the eponymous Lion’s Head pediment that was removed from the Parthenon’s northeast side on Friday 9 June 2011. The pediment was removed from atop the celebrated Classical Era ancient temple for restoration. The Parthenon was painted in bright colours during antiquity, as were most ancient temples, a far cry from the ubiquitous sun-baked and bare marble columns and friezes usually associated today with the Greco-Roman era. ANA-MPA/ORESTIS PANAGIOTOU