Passage 9.2.6
ἄγουσι δὲ καὶ νῦν ἔτι ἀγῶνα διὰ ἔτους πέμπτου τὰ δὲ Ἐλευθέρια, ἐν ᾧ μέγιστα γέρα πρόκειται δρόμου· θέουσι δὲ ὡπλισμένοι πρὸ τοῦ βωμοῦ. τρόπαιον δέ, ὃ τῆς μάχης τῆς Πλαταιᾶσιν ἀνέθεσαν οἱ Ἕλληνες, πεντεκαίδεκα σταδίοις μάλιστα ἕστηκεν ἀπωτέρω τῆς πόλεως.
Even now they still hold a contest every fifth year called the Eleutheria, in which the greatest honours are awarded in the footrace; the competitors run fully armed before the altar. The trophy that the Greeks dedicated after the battle for the Plataeans stands roughly fifteen stadia outside the city.