The Peloponnese looks like a peninsula and is an archipelago of valleys.

Open a map of Greece and the Peloponnese looks like a four-fingered hand hanging from the mainland: the Messenian peninsula, the Mani, Cape Malea and the Argolid. It covers 21,550 square kilometres and had about 1.15 million people in the 2011 census. But the map misleads on the essential point: it suggests a single piece of territory, and inside, almost nothing is connected to anything else.

01 A map that suggests one piece

The name already said so. Peloponnesos means «island of Pelops», a mythological hero the ancients credited with conquering the region. «Island» was not a geographers' mistake: the word was used in its archaic sense, a land almost enclosed. And almost enclosed it was. The only neck joining it to mainland Greece, the Isthmus of Corinth, is only a few kilometres wide.

The ancients already saw it as a place apart. Around 600 BC the Diolkos was paved across the Isthmus of Corinth, a stone track along which ships were hauled from one gulf to the other, and in 1893 the 6,343-metre Corinth Canal was completed, technically making it an island. Until 2004, moreover, it could only be reached through the isthmus or by ferry; that year the Rio-Antirrio bridge opened. Those are the edges. What is interesting, and what the map almost never tells you, is what lies inside.

02 Inside, an archipelago

Here is what changes the reading. If you enter the Peloponnese by the canal or by the bridge expecting continuous territory, geography contradicts you within a few kilometres. Taygetus rises to 2,407 metres; Cyllene to 2,376; Aroania to 2,355; Erymanthos to 2,224. Mainalon and Parnon reach about 1,981 and 1,935. This is the relief of a mountain island, not of a plain with a few hills.

And the rivers do the rest, but on a small scale: the Alfeios, the longest, is 110 kilometres; the Evrotas, 82; the Pineios, 70. They are short rivers that do not join regions but each water its own valley. From this comes a very unusual way of occupying the land: not a network, but compartments. In the Evrotas valley, between Taygetus and Parnon, Sparta grew. On the plain of the Argolid, Argos, Mycenae and Tiryns. In the Alfeios valley, Olympia. Each of those plains was a small island inside the large one.

Ancient Greek cities were independent city-states, and history offers many reasons for that. Here there is also a physical one that helps explain it: each had its plain, its short river and its wall of mountains. Anyone wanting to visit a neighbour crossed a mountain pass. Taygetus, for example, separates the Evrotas valley, to the east, from Messenia, to the west. To get from one side to the other you had to climb and come back down, and that friction, repeated over centuries, produced places different from one another.

03 Olympia, the valley that buried itself

Olympia is the cleanest example. It lies in the valley of the Alfeios, with its tributary the Kladeos running along the site's western edge, about 18 kilometres from the coast of the Gulf of Kyparissia; in antiquity it may have been half that distance. Tradition dates the first Games to 776 BC. And the valley, far from preserving the sanctuary, buried it: alluvial deposits up to eight metres deep covered it. For a long time this was blamed on river floods; more recent research points to repeated tsunamis.

What we see today is a product of that layer of sediment: Richard Chandler rediscovered the place in 1766, a French expedition made the first excavation in 1829 and German excavations began in 1875. The modern Games were restored on a global scale in 1894. The Olympic flame is still lit at the Temple of Hera with a parabolic mirror that reflects the sun. A closed valley that kept, underground, what it was entrusted with.

04 Mystras: a town that changes floors

If the valleys are compartments, the slopes are their other floor. Mystras was built from the winter of 1248-1249 on a slope of Taygetus, above ancient Sparta. From 1349 it was the residence of the despots of the Morea and remained so until 1460. It has an upper town and a lower town, and many of its streets are footpaths, because on that slope wheeled vehicles were impractical. It emptied from the 1830s on, when modern Sparta was laid out on the flat. People came down from the mountain to the plain: the reverse of the movement in 1248.

The medieval name of the place, Morea, which gives the Despotate its title, has a disputed origin. The most widespread explanation links it to the mulberry tree and to the shape of the peninsula, which resembles a mulberry leaf. It is a theory, not a certainty: the name is only documented in Byzantine chronicles of the 10th century. But it works as an image: a leaf with veins, that is, a map of valleys.

05 Monemvasia: an island inside the island

The east coast holds the extreme case. Monemvasia is a rock joined to the land by a sandy tongue about 400 metres long; in 1890, three years before the canal was completed, part of that tongue was cut to open an artificial passage for boats. Its name comes from moni («single») and emvasis («entrance»): the city of the single entrance. It was founded in the 6th century and is one of the oldest continuously inhabited fortified towns in Europe.

In the upper town, the plateau of the rock, about 100 metres above the sea and up to 300 wide by one kilometre long, nobody lives today. The lower town, walled on three sides, had a community of 1,626 inhabitants in the 2021 census. The same logic appears again and again: a place held by a thread (an isthmus, a mountain pass, a single approach) that owes its character to that thread.

06 So how do you read the Peloponnese

What surprises the visitor, and what is most often misunderstood, is the scale. The Peloponnese is not large: 21,550 square kilometres, an area comparable to Slovenia. What it is, is dense in relief. Spending a few days here means moving from one valley to another, and noticing at each mountain crossing that you have changed worlds: another landscape, another stone, another size of village.

That is why it helps to read it the opposite way to a continuous destination. There is no centre from which everything radiates. There is a collection of plains and of places hanging by a thread. If it still looks like a single place, climb to a mountain pass and look both ways.