Anyway, I was designing a ruin -- a dangerous place to explore, with cave-ins, blocked passageways, traps and monsters. And to really do it right, there is one rule that must be obeyed: you must first design it as it was before its fall. If you don't know where everything went and how it was used in its prime, then no matter how exciting the sequence of encounters you plan for its ruins, it won't make sense. Something will be lacking.
I think a lot of books and movies suffer from this lack of depth. The narrative flows from point to point, tension is built up and released, character is revealed, exposition happens. But there are gaping holes in the story. Oh, if you keep the thrills coming, maybe most people won't notice; but if the pace slacks off for even a second, you start to think, this doesn't really make sense.
It seems like a lot of work to plan a huge complex, only to flatten half of it and stuff the remainder with monsters. But if it doesn't start right, it won't end right.