Over the past few days I spent some time looking at 2Co 10.1-6. The ESV is below; note the bold portions:

I, Paul, myself entreat you, by the meekness and gentleness of Christ—I who am humble when face to face with you, but bold toward you when I am away!—I beg of you that when I am present I may not have to show boldness with such confidence as I count on showing against some who suspect us of walking according to the flesh. For though we walk in the flesh, we are not waging war according to the flesh. For the weapons of our warfare are not of the flesh but have divine power to destroy strongholds. We destroy arguments and every lofty opinion raised against the knowledge of God, and take every thought captive to obey Christ, being ready to punish every disobedience, when your obedience is complete. (2Co 10.1-6, ESV)

There's a lot going on here, and I won't mention everything I looked into when I reviewed the passage. But one interesting aspect was Paul's use of the phrase “to destroy strongholds”. The “strongholds” Paul is speaking of are in the realm of ideas — arguments and philosophies that war against the “knowledge of God”. Any of these sorts of arguments or opinions that are contrary to the “knowledge of God” will, Paul says, be destroyed.

Anyway, the Greek phrase translated “to destroy strongholds” is πρὸς καθαίρεσιν ὀχυρωμάτων. Apart from the preposition, these are uncommon words in the NT. ὀχύρωμα (“stronghold”) only occurs here in the NT. καθαίρεσις (“destroy/destruction”) occurs three times in the NT, and all three of these are in 2 Corinthians (here, 2Co 10.8 and 2Co 13.10). The translation “to destroy” is the similar verb καθαιρέω (occurs 9x in NT, only here in 2Cor)

Got it?

Now, check out Philo,* Conf. Ling. §§129-130:

¹²⁹ And the name is, as the Hebrews say, Phanuel, which translated into our language means, “turning away from God.” For any strong building which is erected by means of plausible arguments is not built for the sake of any other object except that of averting and alienating the mind from the honour due to God, than which object what can be more iniquitous? ¹³⁰ But for the destruction of this strong fortification a ravager and an enemy of iniquity is prepared who is always full of hostility towards it; whom the Hebrews call Gideon: which name being interpreted means, “a retreat for robbers.” “For,” says Moses, “Gideon swore to the men of Phanuel, saying, On the day when I return victorious in peace, I will overthrow this tower.”

Paul and Philo are using the same language. The “strong building/fortification” are both ὀχύρωμα. The word translated “destruction” is καθαίρεσις. In both passages, the “strong building/fortification/stronghold” refers not to a physical building, but instead to ideas that war against God. These strongholds will be destroyed.

Now, for the question: How did I find this? Simple. Conf. Ling. §§129-130 is listed as a citation in the BDAG article for ὀχύρωμα. I just hovered over the reference in the LDLS edition and the English of Yonge's edition popped up (you may need to adjust your keylink preferences for Philo). I guessed on the English based on what BDAG implied the Greek would be. Then, when I got to the office, I looked it up in the Greek edition that we're working on and confirmed the presence of the words in question and their translations in Yonge.

* Remember, The Works of Philo: Greek Text with Morphology is under production as a Logos Bible Software resource ... don't be the last one on your block to get a copy!