Revelation 16:19 καὶ ἐγένετο ἡ πόλις ἡ μεγάλη εἰς τρία μέρη καὶ αἱ πόλεις τῶν ἐθνῶν ἔπεσαν. καὶ Βαβυλὼν ἡ μεγάλη ἐμνήσθη ἐνώπιον τοῦ θεοῦ δοῦναι αὐτῇ τὸ ποτήριον τοῦ οἴνου τοῦ θυμοῦ τῆς ὀργῆς αὐτοῦ.
The great city was divided into three parts, and the cities of the nations fell. Babylon the great was remembered in the sight of God, to give to her the cup of the wine of the fierceness of his wrath.
Noun: Nominative Singular Feminine

Revelation 17:5 καὶ ἐπὶ τὸ μέτωπον αὐτῆς ὄνομα γεγραμμένον, μυστήριον. Βαβυλὼν ἡ μεγάλη, ἡ μήτηρ τῶν πορνῶν καὶ τῶν βδελυγμάτων τῆς γῆς.
And on her forehead a name was written, "MYSTERY, BABYLON THE GREAT, THE MOTHER OF THE PROSTITUTES AND OF THE ABOMINATIONS OF THE EARTH."
Noun: Nominative Singular Feminine

Revelation 18:2 καὶ ἔκραξεν ἐν ἰσχυρᾷ φωνῇ λέγων, ἔπεσεν ἔπεσεν Βαβυλὼν ἡ μεγάλη, καὶ ἐγένετο κατοικητήριον δαιμονίων καὶ φυλακὴ παντὸς πνεύματος ἀκαθάρτου καὶ φυλακὴ παντὸς ὀρνέου ἀκαθάρτου [καὶ φυλακὴ παντὸς θηρίου ἀκαθάρτου] καὶ μεμισημένου,
He cried with a mighty voice, saying, "Fallen, fallen is Babylon the great, and she has become a habitation of demons, a prison of every unclean spirit, and a prison of every unclean and hateful bird!
Noun: Nominative Singular Feminine

Revelation 18:10 ἀπὸ μακρόθεν ἑστηκότες διὰ τὸν φόβον τοῦ βασανισμοῦ αὐτῆς λέγοντες, οὐαὶ οὐαί ἡ πόλις ἡ μεγάλη, Βαβυλὼν ἡ πόλις ἡ ἰσχυρά, ὅτι μιᾷ ὥρᾳ ἦλθεν ἡ κρίσις σου
standing far away for the fear of her torment, saying, 'Woe, woe, the great city, Babylon, the strong city! For your judgment has come in one hour.'
Noun: Vocative Singular Feminine

Revelation 18:21 Καὶ ἦρεν εἷς ἄγγελος ἰσχυρὸς λίθον ὡς μύλινον μέγαν καὶ ἔβαλεν εἰς τὴν θάλασσαν λέγων, οὕτως ὁρμήματι βληθήσεται Βαβυλὼν ἡ μεγάλη πόλις καὶ οὐ μὴ εὑρεθῇ ἔτι.
A mighty angel took up a stone like a great millstone and cast it into the sea, saying, "Thus with violence will Babylon, the great city, be thrown down, and will be found no more at all.
Noun: Nominative Singular Feminine