Passage 2.16.5
Μυκήνας δὲ Ἀργεῖοι καθεῖλον ὑπὸ ζηλοτυπίας. ἡσυχαζόντων γὰρ τῶν Ἀργείων κατὰ τὴν ἐπιστρατείαν τοῦ Μήδου, Μυκηναῖοι πέμπουσιν ἐς Θερμοπύλας ὀγδοήκοντα ἄνδρας, οἳ Λακεδαιμονίοις μετέσχον τοῦ ἔργου· τοῦτο ἤνεγκεν ὄλεθρόν σφισι τὸ φιλοτίμημα παροξῦναν Ἀργείους. λείπεται δὲ ὅμως ἔτι καὶ ἄλλα τοῦ περιβόλου καὶ ἡ πύλη, λέοντες δὲ ἐφεστήκασιν αὐτῇ· Κυκλώπων δὲ καὶ ταῦτα ἔργα εἶναι λέγουσιν, οἳ Προίτῳ τὸ τεῖχος ἐποίησαν ἐν Τίρυνθι.
The Argives destroyed Mycenae out of jealousy. For while the Argives remained passive during the expedition against the Mede, the Mycenaeans dispatched eighty men to Thermopylae who shared with the Lacedaemonians in that task. It was this ambition of theirs that provoked the Argives and brought about their ruin. Yet part of the surrounding wall still remains, along with the gate upon which stand lions. These, too, are said to be works of the Cyclopes, who also constructed the walls at Tiryns for Proetus.