Raise your eyes nearly anywhere in Athens and you're likely to be stopped in your tracks by the sight of the Acropolis, where Pericles rose to the heights of power and creative achievement, with the construction of the Parthenon and Propylaea. After a time-trip to the golden age of Greece, explore modern Athens's patchwork of neighborhoods to get a sense of the history of this gregarious city, its people, and what lies beyond the ubiquitous modern concrete facades. Take in a twilight view from Athenians' favorite "violet-crowned" aerie, Mt. Lycabettus, and drink in the twinkling lights of the metropolis that is home to more than 4 million souls, still growing and still counting.
The best times to visit the city are late fall and spring, when you can avoid the oppressive heat and the hordes of package tourists at major archaeological sites; you can also enjoy the bustling nightlife in the center, because after June many restaurants and clubs shut down or relocate to the seaside. Holy Week of the Orthodox Easter, usually in April or May, is a chance to observe Greece's most sacred holiday, including mournful Good Friday processions accompanying Christ's bier, and the candlelit Easter midnight service, complete with fireworks.
Many major sights, as well as hotels, cafés, and restaurants, are within a fairly small central area. It's easy to walk everywhere, though sidewalks are sometimes obstructed by parked cars.
If You Have 1 Day: Early in the morning, pay homage to Athens's most impressive monument, the Acropolis. Then descend through Anafiotika, the closest thing you'll find to an island village on the mainland. Explore the 19th-century quarter of Plaka, with its neoclassical houses, and stop for lunch at one of its many tavernas. Do a little bargaining with the merchants in the old Turkish bazaar around Monastiraki Square. Spend a couple of hours in the afternoon taking in the stunning collection of antiquities in the National Archaeological Museum (check to be sure it's open); then pass by Syntagma Square to watch the changing of the costumed Evzone guards in front of the Tomb of the Unknown Soldier. You can then window-shop or people-watch in the tony neighborhood of Kolonaki. Nearby, take the funicular up to Mt. Lycabettus for the sunset before enjoying a show at the Odeon of Herod Atticus, followed by dinner in the funky district of Psirri.