The Persian invasion of Greece can be summarized as follows:
Persian King Darius I sought to punish the Greeks for their part in the Ionian revolt.
He sends an invasion force which subjugates Thrace and Macedonia in 492 B.C. but the Persian fleet is destroyed in a storm and the army forced to withdraw.
A second expedition in 490 sets up the Battle of Marathon where the Persians are defeated.
In 480, Darius’ son Xerxes invades again, clearing the way to Attica by defeating the Greeks at Thermopylae in 480.
Xerxes sacks Athens and is planning an invasion of the Peloponnese when he is defeated at the naval battle at Salamis.
Xerxes retreats from Greece for good after the Battle of Plataea in 479.
The invasion of 480 included the sack of Athens. Unprepared to resist the invading force, the Greeks abandoned the city and headed south to save themselves. A token non-official force remained on the Acropolis. As our friend Herodotus tells us, “The Persians found Athens abandoned except for a few people in the temple of Athene Polias – temple stewards and needy folk.”
They tried to resist the Persian troops by rolling boulders down the slope of the Acropolis, but were eventually overrun when an unguarded section was the slope was successfully scaled. The following day the Persians looted the Acropolis of its treasures and destroyed most of the sacred buildings. The rebuilding of the site was completed sixty years later during the Peloponnesian War.