The Argolid is the northeastern finger of the Peloponnese, and it packs more ancient Greek history into a small area than almost anywhere else in the country. Mycenae, Epidaurus, Tiryns, and ancient Argos are all here, spread across a landscape of olive groves, orange orchards, and dry hills that has not changed all that much since Agamemnon's time.
Nafplio, the region's main town and Greece's first capital after independence, is the natural base. It is one of the most attractive small towns in Greece, with a Venetian old town, a fortress on the headland, and a waterfront lined with cafes. From Nafplio, Mycenae and Epidaurus are each about a half-hour drive, making it easy to visit the great sites without rushing.
Epidaurus has the most perfectly preserved ancient theater in Greece. Its acoustics are famous and genuinely astonishing: a coin dropped on the stage can be heard in the back row. The theater still hosts performances during the Athens and Epidaurus Festival each summer. Mycenae, the fortress-palace of the Mycenaean civilization, sits on a hilltop commanding the plain. The Lion Gate, the Treasury of Atreus, and the massive Cyclopean walls are powerful even in ruin. Tiryns, closer to Nafplio, has walls so enormous that the ancients believed only the Cyclopes could have built them.
The region is easy to reach from Athens, about two hours by car or bus via Corinth. You could see the highlights in a long day trip, but staying a night or two in Nafplio is strongly recommended.