The Termòpili or, more correctly, the Termòpile (in ancient Greek: Θερμοπύλαι, in Greek: Θερμοπύλες) are a Greek locality where in ancient times there was a narrow coastal passage. The name means "hot doors" and derives from the presence of numerous natural hot water springs.
It is best known for the battle of Thermopylae in 480 BC, in which a small Greek force commanded by the king of Sparta Leonidas I and composed of various contingents, among which the Spartan chosen soldiers stood out, slowed down the advance of the Persian army commanded by Xerxes I at the cost of almost complete destruction; since then the term "thermopylae" has been used to indicate a tragic and heroic resistance against a much more powerful enemy.
Now a new main road divides the pass, and the modern monument to Leonidas is to the east of it. The road crosses the hill where the epitaph of Simonides is engraved in the stone. Thermopylae is also sadly known as the "horseshoe of Maliakos" or "horseshoe of death": here is the narrowest part of the road that connects the north and south of Greece, which has many curves and has been of many automobile accidents.
The locality is an almost obligatory passage along the main Greek north-south route between Locride and Thessaly and for this reason it has been the scene of numerous battles.
The passage was located between Mount Eta and an inaccessible marsh which constituted the limit of the Gulf of Malia. Due to the variation in the course of the rivers and the consequent change in the configuration of the coast, Thermopylae are now very different from how they once appeared, so it must be taken into account that the data reported by Herodotus and other ancient authors refer to a situation different from the current one.
At the time of Herodotus the Spercheo river flowed towards the sea east of the city of Anticira, decidedly west of the passage; twenty stadia east of the aforesaid river there was another, the Dira, and again, at another twenty stadia, a third, the Melas, five stadiums away from the city of Eraclea Trachinia. Between the mountains where Eraclea Trachinia was and the sea, the plain became wider. Further east was the Asopo, which flowed from a rocky gorge, and to the east is a small stream, called the Phoenix, which flows into the Asopo. From the Phoenix to the Thermopylae pass, according to Herodotus, there were fifteen stages. Near the union of the two rivers, Mount Eta came so close to the pond that only one chariot could pass. In the immediate vicinity of the pass was the city of Antela, famous for the temples of Amphionia and Demeter Amphitionic, where the seats of the members of the Amphictyonic council, which held its autumn meetings here, were located. In Antela, Mount Eta moved slightly away from the coast, thus leaving room for a plain less than a kilometer wide; in Alpeni, the first city of Locride, the space narrowed again until only one wagon could pass at a time.
In Thermopylae there were some hot springs consecrated to Hercules, which were called in ancient Greek: χύτραι, that is "pots", alluding to the cells prepared for bathers. Here the Phocians had in ancient times built a wall to defend their country from the attacks of the Thessalians and they had left it in order to divert the waters and make the passage impassable. From this we learn that the real Thermopylae were located near Alpeni, but the name has also been applied to the entire area between the mouth of the Asopo and Alpeni.
Thermopylae, therefore, consisted of two narrow passages with a plain in the middle of just under two kilometers in length and less than one in width. The part of Mount Eta that overlooked Thermopylae is called Callidromo by Tito Livio and by Strabo, but entered