It is possible to see most of the Ancient Stuff around Athens in 1 day, but 2 days would be best.
Most of the Ancient Stuff around Athens is clustered in one area—the Acropolis ("upper city") and surrounding land just below. The Acropolis is a giant limestone bench, perhaps 100m high, which dominates the landscape. Originally the site of more ancient temples, which have long since disappeared, the structures that stand on top of the Acropolis today are the Parthenon, the Erechtheion, and the Temple of Athena Nike. All were constructed in the 5th century BC.
We entered the Acropolis area from the west side. Bags are not allowed, so we checked our backpacks at the booth. After passing through the gate, but before reaching the top, we stopped to look over the edge to the south/southwest. Here we were able to see down into the Theatre of Herod Atticus, built in 161 AD, and still used for theatre, ballet, and musical performances.
Continuing to the top, we first passed through a gateway of columns and buildings under scaffolding, called the Propylaea. On the other side, the three temples rose up into the sky even higher, and there were crowds of people around each one.
The Parthenon is dedicated to Athena, the patron goddess of Athens. Greek mythology says that Athena was the daughter of the supreme god Zeus and Metis. While Metis was pregnant with Athena, a prediction was made that the next child after Athena would overthrow Zeus, so Zeus proceeded to swallow Metis (logical, yes, I know). Anyway, Athena was then born out of Zeus’s head, and became the Olympian goddess of war and wisdom, and crafts and domestic arts. Athena was a virgin.
Athena became the patron goddess of Athens after a battle with her uncle Poseidon (brother of Zeus). On top of the Acropolis, Poseidon drove his fork into the ground, causing salt water to flow, in an effort to show his worthiness to the people of Athens. Athena planted an olive tree, which was deemed the greater act, and she became the patron goddess. On the site of the "battle" between Athena and Poseidon is the Erechtheion. The eye-catcher on the Erechtheion is the porch of the Maidens of Caryatids.
The third temple on top of the Acropolis is the Temple of Athena Nike, built in honor of Athena’s victory over the Persians. Athena avoided war, but when forced to fight, was said to be nearly invincible.
Unfortunately, Athena wasn’t around during the 17th-century war between the Turks and the Venetians. If she was, maybe the Turks would not have used the Parthenon as a powder magazine, which exploded when hit by a Venetian bomb, destroying much of the temple and surroundings. The temples have been partially refurbished, but there is still plenty of scaffolding around to block the views.
Make sure to check out the small underground museum west of the Parthenon as well. Much is preserved in the museum, but most of the main statuary was either destroyed or stolen. The thief is alleged to be a British ambassador who took items that are now in the British Museum.