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The entrance to the ancient Eupalinos Tunnel on Samos

Eupalinos Tunnel — A 6th-Century BC Marvel

Everything you need to know before visiting the Eupalinos Tunnel on Samos: the 6th-century BC aqueduct dug from both ends through a mountain, why it matters, and how to fit it into a Pythagoreio day.

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About an hour Above Pythagoreio, south-east coast Check access before you go

One of the great feats of ancient engineering: a 6th-century BC aqueduct tunnel dug through Mount Kastro from both ends, its two teams meeting almost perfectly in the middle. It was built to bring water to the ancient city and is part of the UNESCO-listed Pythagoreio site. You walk a stretch of it, so it suits anyone who's happy with a low ceiling and a dim passage. Comfortable shoes help; claustrophobia doesn't.

What to see and do

  • The tunnel itself — the headline attraction — the accessible section shows the cut and gives you a real feel for the scale of the job.
  • The engineering story — digging simultaneously from both ends through solid rock, and meeting close to the centre, is what makes it famous.
  • The view over Pythagoreio — the tunnel sits above the town, so it pairs naturally with a walk or drive around the harbour.
  • A quick stop — about an hour covers it — a good add-on rather than a full-day plan.

Tours to the Eupalinos Tunnel

No tunnel-specific tour is confirmed yet — most visitors drive or taxi up from Pythagoreio. Browse every verified Samos tour for organised options.

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Frequently asked questions

You can enter and walk part of it, but access has varied over the years, so check the current arrangements locally before you make it the centrepiece of a day.

Explore Pythagoreio

It's a 6th-century BC aqueduct dug from both ends through Mount Kastro, with the two teams meeting almost perfectly in the middle — a celebrated ancient-engineering achievement.

Read the full Samos travel guide

The Heraion and Pythagoreio's harbour and castle are both a short drive away, so all three fit into a single day.

Add the Heraion of Samos

Practical details (opening times, prices) change — verify before you go. Last updated September 2026.