It became famous after the battle information was used in literature, comics, cinema and computer games. The battle is not fictional, the events described in the book of Herodotus were confirmed by numerous archaeological excavations.
The description of the battle is familiar to everyone. The Persian king Xerxes, expanding his possessions, seized one state after another, heading south of modern Greece. From 5 to 7 thousand of Greeks came to fight against the 250-thousand army of the Persians. Despite such a huge difference in strength, the Greeks chose the perfect place to fight - a narrow strip of land between the sea and the mountains (Thermopylae). The width of the land was 40-50 meters and in some places it narrowed to 5 meters.
For two days they successfully fought off the attack, killing at least 20 thousand Persians, but then, fearing the encirclement, retreated. Only 500 people left to protect the pass: the Spartan king Leonid, his 299 soldiers, and also 200 Thespians and the Thebans. The number of Spartans was exactly 300, this is not a made-up figure for a beautiful movie title. Despite the heroism they all died. Check Wikipedia for a full description of the battle.
At the moment, the Thermopylae pass is impossible to see. The sea has moved away from the mountains for at least 3 kilometers. You can see it only from above.
Nowadays there is a memorial on the battlefield and also a historical information center dedicated to the battle.
The inscription on the monument says: "Come and take". This is the correct phrase of his answer to the ambassador of the Persians, and not "This is Sparta!" which became a famous meme.
Getting there: the monument is located near the country's main autobahn, so almost all tourists are brought here. Parking N 38 47.803 E 22 32.193. The place is located outside the cities, so getting by public transport is inconvenient. At first by bus Athens - Lamia (schedule) and then either by taxi to the monument or by local bus. Given the price of a taxi (up to 10 euros one way), it makes no sense to search for a bus.