The Vale of Tempe is a strategic connecting route between Olympus to the north and Ossa to the south, and between the regions of Thessaly and Macedonia. The valley is 10 kilometers long and as narrow as 25 meters in places, with cliffs nearly 500 meters high, cut by the Pineios River on its way to the Aegean Sea. In ancient times, it was celebrated by Greek poets as a favorite haunt of Apollo and the Muses. On the right bank of the Pineios sat a temple to Apollo, near which the laurels used to crown the victorious in the Pythian Games were gathered. The Tempe Pass is a strategic pass in Greece since it is the main route from Larisa through the mountains to the coast. Though it can be bypassed via the Sarantoporo Pass, the alternative route takes longer. Because of this it has been the scene of numerous battles throughout history. In 480 BC, 10,000 Athenians and Spartans gathered at Tempe to stop Xerxes's invasion. However, once there, they were warned by Alexander I of Macedon that the vale could be bypassed and that the army of Xerxes was overwhelmingly large; accordingly, the Greeks retreated. en.wikipedia.org/wiki/Vale_of_Tempe