Western medicine was born on this island. Hippocrates, the father of the healing arts, was born on Kos nearly two thousand five hundred years ago, and his benevolent shadow still hovers over the squares, the ruins and even beneath the branches of a venerable plane tree. Ships dock in the heart of the main town, facing a castle of the Knights of St. John: rarely does a Dodecanese port call put so much history within immediate reach of the gangway.

Neratzia, Sentinel of the Harbour

Neratzia Castle has guarded the harbour entrance since the days of the Knights of St. John, who built it by reusing ancient marble found on site. Its massive walls, set between palm trees and sailboats, set the tone as soon as you step onto the quay. Depending on the period, the interior is open to visitors or can be admired from outside; either way, walking around its ramparts along the palm-lined avenue is well worth it. In the walls, a trained eye will spot column drums and carved blocks: the medieval builders literally recycled the ancient city to raise their fortress.

The Plane Tree of Hippocrates

Directly opposite the castle entrance, on Platanou Square, an immense tree spreads its branches, held up by props. Tradition has it that Hippocrates taught beneath its ancestor; the current plane tree, at most five centuries old, keeps the memory alive with the dignity of a patriarch. Medical students from around the world come to have their picture taken here, and despite the crowds, the place retains something moving: a simple tree as a monument to the birth of a science. You linger a moment beneath the foliage, listening to guides tell the same story in five languages.

The Agora and a Walkable Town

Just steps from the square, the ruins of the ancient agora spread out right in the centre: columns, mosaics and foundations slumber among the hibiscus, freely accessible or nearly so. Kos is easy to explore, flat as a pancake, and locals happily get around by bicycle; bike paths are as much a part of the urban landscape as scooters. Between sites, the shopping streets offer plenty of patios where you can sip a frappé in the shade, while sponge and thyme honey vendors cheerfully call out to passersby.

The Asclepieion, the Hospital of Antiquity

Four kilometres to the northwest rise the terraces of the Asclepieion, the most famous healing sanctuary of the Greek world, closely linked to the school of medicine born on the island. Temples, porticoes and monumental staircases are layered here facing the sea and the Turkish coast. From the upper terrace, the view stretches far across the strait, and you understand why the ancients chose this hillside to heal bodies and minds alike. A small tourist train leaves from the marina for about five euros round trip, unless you prefer a taxi or a bike. Allow an hour and a half on site to grasp the spirit of the place.

Practical Pointers

• Docking in the centre of Kos; the castle, legendary tree and agora are a few minutes' walk away.
• Asclepieion: 4 km; small train from the marina (about 5 euros round trip), taxi or bike.
• Flat terrain: cycling is an excellent way to explore the town.
• Bring water and a hat for the Asclepieion, which has little shade in summer.

Heading back to the ship, you inevitably pass the old tree again, where evening visitors are still seeking a bit of its shade. Two and a half millennia later, the island continues to do exactly what its most illustrious son recommended: care for people, if only by offering them a day of walking in the sun, between the sea and memory.