National Archaeological Museum

The National Archaeological Museum is where the headline objects of Greek civilisation actually live, and it is criminally under-visited compared with the rock — a nineteenth-century treasury thirty minutes' walk north of the centre that repays them better than any site except the Acropolis itself.

Four things justify the trip alone. The Mask of Agamemnon, the hammered-gold funeral face Heinrich Schliemann lifted from a Mycenaean shaft grave in 1876 and telegraphed the king's name around the world (it's three centuries too old to be Agamemnon; nobody has ever cared). The Artemision Bronze, a two-metre Zeus — or Poseidon; the missing weapon settles the argument — frozen mid-throw, fished from a shipwreck in 1926 and displayed with an entire room to swagger in. The Jockey of Artemision from the same wreck, a boy and racehorse at full gallop, the most kinetic object antiquity left us. And the Antikythera Mechanism: the corroded bronze gear-train from a 1st-century-BC wreck that turned out to be a hand-cranked astronomical computer predicting eclipses and planetary positions — two thousand years before anything comparable exists again. Its gallery, with the X-ray reconstructions, is quietly mind-bending.

Upstairs, the frescoes of Akrotiri — the Bronze Age Pompeii buried by the Santorini eruption around 1600 BC — keep their colour like they were painted last spring: boys boxing, antelopes, a whole miniature fleet. Most visitors never find the staircase. Find the staircase.

Give it a morning, take the museum café's sculpture-garden courtyard in the middle as an intermission, and don't attempt completeness — the Mycenaean hall, the bronzes, the Antikythera room and Akrotiri are the spine, and they're plenty. It pairs naturally with the Exarcheia neighbourhood's lunch places two streets behind.