If you've been to a fort, you know there's this mindfuckery going on with how the walls are angled. It's easy to think today that places are easy to take, because there's now airplanes. But then look at Ukraine and you can see that's not how it is.

The jews also can't budge the underground fortress of Gaza that way. Once you understand you have to walk into this place, you start realizing why they built them like this, and the meaning of "impenetrable".