Two days in Athens is enough to see the ancient sites that make this city legendary, from the hilltop temples of the Acropolis to the marble stadium of the first modern Olympics. This itinerary splits the essentials into a classical-history day and a museums-and-squares day, so you're never rushing between sites.
Arrive early at the Acropolis to walk among the Parthenon and the graceful Erechtheion before the midday heat and crowds set in. Head downhill to the Acropolis Museum, where glass floors and floor-to-ceiling windows put the excavated ruins and original sculptures in direct view of the hill they came from. After lunch, wander the Ancient Agora, once the civic heart of Athens, then continue to the nearby Roman Agora and the Library of Hadrian. End the day browsing the stalls around Monastiraki Square, where flea-market energy meets views straight up to the Acropolis.
Start at the towering columns of the Temple of Olympian Zeus, just steps from the ancient Hadrian's Arch. Walk over to the Panathenaic Stadium, the all-marble arena built for the first modern Olympic Games in 1896. In the afternoon, head north to the National Archaeological Museum for its unmatched collection of Greek antiquities, from Mycenaean gold to classical bronzes. Finish in the city center at Syntagma Square, timing your visit to catch the changing of the guard, before a relaxed dinner nearby.