Still, the political pre-eminence of Athens during the fifth century BC certainly had an important part to play in the progress of the Greek Revolution. In the final decades of the Archaic age, the great enemy of the Greeks was Persia. In 490BC, the Persians set foot on mainland Greece – resulting in the Battle of Marathon, which the Greeks won against the odds. In 480BC, though, the Persians returned, and this time they made it all the way to Athens, which they sacked. After the Persians were finally defeated, in 479BC, Athenian self-confidence soared. Under Pericles, the citizens of Athens decided to rebuild the devastated Acropolis, which was like an Athenian Ground Zero. Building began on the mammoth project of the Parthenon.