Passage 5.10.1
πολλὰ μὲν δὴ καὶ ἄλλα ἴδοι τις ἂν ἐν Ἕλλησι, τὰ δὲ καὶ ἀκούσαι θαύματος ἄξια· μάλιστα δὲ τοῖς Ἐλευσῖνι δρωμένοις καὶ ἀγῶνι τῷ ἐν Ὀλυμπίᾳ μέτεστιν ἐκ θεοῦ φροντίδος. τὸ δὲ ἄλσος τὸ ἱερὸν τοῦ Διὸς παραποιήσαντες τὸ ὄνομα Ἄλτιν ἐκ παλαιοῦ καλοῦσι· καὶ δὴ καὶ Πινδάρῳ ποιήσαντι ἐς ἄνδρα Ὀλυμπιονίκην ᾆσμα Ἄλτις ἐπωνόμασται τὸ χωρίον.
Indeed one could observe many other notable things among the Greeks, and also hear many things worthy of wonder; but above all, the mysteries performed at Eleusis and the contest held at Olympia receive special care from the god. As for the sacred grove of Zeus, its name has long ago been altered, and it has been called the "Altis" since ancient times. Indeed, even in a poem composed by Pindar about an Olympic victor, this place is called "Altis."