Athens is the main gateway to the Greek islands, and many visitors use it as a base for island-hopping. But there are good day trips within reach without a ferry.
Cape Sounion, 90 km south of Athens, has the clifftop Temple of Poseidon perched dramatically above the sea. Buses run from the Pedion Areos park terminal, taking about 2 hours. Lord Byron carved his name into the base of a column here, which in any other country would be considered vandalism.
Delphi, three hours north-west by bus from the Liosion terminal, was the most sacred site in the ancient Greek world — the Oracle, the Temple of Apollo, the Treasury of the Athenians, and the stadium above. A full day is enough; the site museum is excellent. A comfortable day trip if you start early.
Epidaurus, in the Peloponnese about 2.5 hours by bus, has the best-preserved ancient theatre in Greece — 14,000 seats with acoustics so perfect that you can hear a coin drop on stage from the top row. Part of the Athens Epidaurus Festival programme is staged here in summer.