ACROPOLIS. The Acropolis is the jewel in Athens' crown. In 510 BC, Pericles set about transforming the "High City" ­ where people had been living since 5,000 BC ­ into a city of temples. The most famous of these is the Parthenon, dedicated to (and meant to house a giant statue of) the goddess Athena. Once painted in bright colors, the Parthenon is still breathtaking, despite its subdued marble façade. The Acropolis is also site of the Erechtheion, where six caryatids serve as columns. Your ticket to the Acropolis is good for a week and includes admission to the Acropolis Museum, the Ancient Agora, the Theater of Dionysus, Karameikos Cemetery, the Roman Forum, the Tower of the Winds and the Temple of Zeus.

MONASTIRAKI. At first glance, this jumbled collection of temples and ruins might not seem like much, but the Agora is one of Athens' most historically significant sites. Agora means "market," and in addition to its commercial focus, it was the city's administrative, political, and cultural center for many years. Socrates lectured from the Stoa of Zeus Eleutherios in the northeast corner and drank his lethal cup of hemlock in the southwest corner. The Agora Museum displays a model of how the ancient site looked when complete and offers exhibits about the Agora's role in Athenian life. Be sure, too, to view Byzantine frescoes at the site's Church of Holy Apostles, a sanctuary built in the 11th century for city Christians.

SYNTAGMA. Built for the Emperor Hadrian in 131 AD, this arch was constructed to separate old Athens from the newer, Roman-built portion of the city. Inscriptions on each side of the arch indicate as much: "This is Athens, the ancient city of Theseus" faces the Acropolis, while "This is the City of Hadrian and not of Theseus" distinguishes the side where Roman ruins have now all but disappeared. The arch rests on ornate Corinthian columns and sits at the intersection of several main roads.

MONASTIRAKI. Rediscovered during road excavations in 1861, this ancient burial ground was used from the 12th century BC until Roman times. Wealthy citizens were buried at the Street of Tombs, whose bas-relief monuments are still worth a look. Pericles himself oversaw the collective funeral for Athenian soldiers interred here after they were killed in the first year of the Peloponnesian War. A small museum features vases, ceramics, and other relics from the graves.

MARATHONAS. Although it's 26 miles outside the city, this site marks Athens' most famous military victory and the run immediately afterwards to announce the news (which inspired the modern-day marathon). In 490 BC at this spot, Persians marched against Athenian troops, and although outnumbered 24,000 to 9,000, the Athenians slaughtered their opponents handily. They then sent their swiftest runner, Pheidippides, to alert the city of victory. Entering the Agora, he shouted "We have won" and promptly dropped dead from exhaustion. Marathonas' burial mound holds cremated remains of the 192 Athenians who fell in battle that day. A small museum in the village offers detailed exhibits about battles fought in the area.