By 454 Athens moved the treasury of the Delian League from the Island of Delos to the Parthenon in Athens. Benefitting greatly from the influx of cash coming out of the 150-330 members, Athens used the money to reinforce its own naval supremacy and used the remaining funds to embellish the city with art and architecture.
The transfer of the Delian League's treasury from Delos to the Parthenon in Athens by 454 Athens allowed them to strengthen their navy and invest in art and architecture within the city.