Thermopylae, Narrow coastal pass in Lamia Municipality, Greece

Thermopylae is a narrow pass in Lamia Municipality, Greece, running between the forested limestone slopes of Mount Oeta and the plain of the Spercheios river. The A1 motorway between Athens and Thessaloniki now follows the ancient shoreline and splits the pass. Hot sulphur springs still rise near the foot of the hill, and travertine deposits from them have helped reshape the ground.

In 480 BC, a small Greek force led by Spartans held this passage for three days against the Persian army. The battle ended after a betrayal, when Persian troops used a mountain trail to outflank the defenders.

The name Thermopylae means "hot gates", after the sulphur springs still flowing near the foot of the hill. The springs were linked to the entrance to Hades, and one version of the Labours of Heracles says the waters turned hot when he washed off the Hydra's poison. The first Amphictyony, a league of Greek tribes, met at nearby Anthela around the cult of Demeter.

The A1 motorway between Athens and Thessaloniki now runs along the ancient shoreline and splits the pass. The monument to Leonidas I stands on the east side of the highway, opposite the hill where Simonides' epitaph is engraved in stone at the top. The road is the narrowest part of the route between northern and southern Greece, with many turns and a record of accidents, so drive with care.

The original passage measured only around 12 meters (40 feet) wide between the cliffs and the water, but sediment deposits have pushed the coastline far out to sea over the centuries. What was once a natural trap is now an open plain with several kilometers of distance between the mountains and the shore.