Reminds me of Arthurian legend, oddly enough. I remember when I was young, reading some Arthurian legend and the castle of Tintagel being described as being so defensible as to be able to be held by three armed men against an entire army. Always had trouble imagining what that would look like as reality rather than exaggeration or hyperbole.

I, uh, think India has a pretty good example here.

As long as the Romans don’t start piling rubble up one side of it, at least.