Passage 1.21.3
οὗτος μὲν ταῦτα ἔλεγεν· ἐπὶ δὲ τοῦ Νοτίου καλουμένου τείχους, ὃ τῆς ἀκροπόλεως ἐς τὸ θέατρόν ἐστι τετραμμένον, ἐπὶ τούτου Μεδούσης τῆς Γοργόνος ἐπίχρυσος ἀνάκειται κεφαλή, καὶ περὶ αὐτὴν αἰγὶς πεποίηται. ἐν δὲ τῇ κορυφῇ τοῦ θεάτρου σπήλαιόν ἐστιν ἐν ταῖς πέτραις ὑπὸ τὴν ἀκρόπολιν· τρίπους δὲ ἔπεστι καὶ τούτῳ· Ἀπόλλων δὲ ἐν αὐτῷ καὶ Ἄρτεμις τοὺς παῖδάς εἰσιν ἀναιροῦντες τοὺς Νιόβης. ταύτην τὴν Νιόβην καὶ αὐτὸς εἶδον ἀνελθὼν ἐς τὸν Σίπυλον τὸ ὄρος· ἡ δὲ πλησίον μὲν πέτρα καὶ κρημνός ἐστιν οὐδὲν παρόντι σχῆμα παρεχόμενος γυναικὸς οὔτε ἄλλως οὔτε πενθούσης· εἰ δέ γε πορρωτέρω γένοιο, δεδακρυμένην δόξεις ὁρᾶν καὶ κατηφῆ γυναῖκα.
These things he related. Upon the wall known as the Southern, which faces toward the theater from the Acropolis, there is placed a gilded head of Medusa the Gorgon, and around it is fashioned an aegis. At the very top of the theater, under the Acropolis and among the rocks, is a cave. Above this also stands a tripod. Within the cave, Apollo and Artemis are depicted slaying the children of Niobe. This same Niobe I myself saw when I ascended Mount Sipylus: from near at hand it is simply a rock and cliff, showing no resemblance whatsoever either to a woman or to one grieving; but if you go a little further away, it seems indeed like a woman bowed down in sorrow, shedding tears.