Have you ever thought of whatever you put your trust in as your own personal "fortified city"? Proverbs 19:10-11 says "The name of the LORD is a strong tower; the righteous run to it and are safe. The wealth of the rich is their fortified city; they imagine it an unscalable wall." So there are really two options here. We can either make Jesus our fortified city, our place of refuge and shelter, or we can make our own achievements and wealth our fortified city. The choice is ultimately up to us who we will choose to trust and obey.
Fortified cities begin when they are built. What fortified city are your building today? One on Jesus or one on yourself?