Passage 8.10.1
ἐς Ἀρκαδίαν δὲ τὴν ἄλλην εἰσὶν ἐκ Μαντινείας ὁδοί· ὁπόσα δὲ ἐφʼ ἑκάστης αὐτῶν μάλιστα ἦν θέας ἄξια, ἐπέξειμι καὶ ταῦτα. ἰόντι ἐς Τεγέαν ἐστὶν ἐν ἀριστερᾷ τῆς λεωφόρου παρὰ τοῖς Μαντινέων τείχεσι χωρίον ἐς τῶν ἵππων τὸν δρόμον καὶ οὐ πόρρω τούτου στάδιον, ἔνθα ἐπὶ τῷ Ἀντίνῳ τὸν ἀγῶνα τιθέασιν. ὑπὲρ δὲ τοῦ σταδίου τὸ ὄρος ἐστὶ τὸ Ἀλήσιον, διὰ τὴν ἄλην ὥς φασι καλούμενον τὴν Ῥέας, καὶ Δήμητρος ἄλσος ἐν τῷ ὄρει.
From Mantineia into the rest of Arcadia there are roads; I shall also describe whatever along each of them is especially worthy of attention. Taking the road to Tegea, on the left side of the highway near the walls of Mantineia, there is land prepared for horse-races, and not far from it a stadium where contests are held in honor of Antinous. Above this stadium rises Mount Alesion, so named, as they say, from the wandering (alē) of Rhea. On the mountain is also a sacred grove of Demeter.