The National Archaeological Museum is the best reason to walk this corner of Athens, and the park behind it is the best reason to stay. This is a short walk with one enormous anchor: a couple of unhurried hours among the finest antiquities in the world, then green air to recover in.
Start at the museum. Inside are the Mask of Agamemnon, the Antikythera Mechanism, the great bronze of Poseidon caught mid-throw — but the trick is not to see everything. Pick three rooms, sit when your eyes tire, and leave with something left over. The neoclassical facade and its palm forecourt are worth a pause of their own.
Then walk north through the edge of Exarcheia — bookshops, murals, the student quarter wearing its politics in paint — to Pedion tou Areos, the city's largest central park. Its grand allée is lined with marble busts of the heroes of 1821; it was laid out as a memorial to the War of Independence. Walk the spine past the bronze Athena, then drop out at Plateia Aigyptou and back to Victoria.