I originally posted this on Google+. However, I wanted to make sure it got a wider distribution. Someone had made a post about why David Hargrave employed so many secret doors on his maps. Naturally it lead to some discussion. See below.
Since this fits in one of the areas I was going to talk about, I'll start here. DH had a good eye for things. It went back to his time as a combat photographer in Vietnam. He also had an appreciation for the realistic side as well, though he didn't let it get in the way of having fun or for making something colorful and cinematic happen.
How does this apply to the question? Well, if you take a look at his design toolbox, DH employed secret doors like they are meant to be. Some are blinds; traps to draw the enemy in and delay, destroy or denude them. Others were fast routes to different parts of the dungeon, facilitating a hidden highway for the denizens (and sometimes intruders). What helps the person that lives there is easy to turn around on them – if you have the knowledge. Some were just whimsical; a play toward the fun side of gaming.
While DH was locked down to a certain mentality in some ways (all encounter rooms pretty much were cookie cutter in the regard of having a monster + treasure in a box, at least in his published works) he was flexible in others. He employed what he learned as a soldier in combat to situations and his eye as a photographer to add some realism to his games. If you look at the times, maps produced back then lacked rhyme and reason for their construction as a general theme – no architect would have made them in life! But they make great gaming tools and draw in the player, pulling them into a world where adventure perches like a gleaming jewel to be found.
What he added was the flavor of some realism, something a few might find odd to apply but its true nonetheless. If you study his maps, you'll see secret doors, sliding walls, and traps everywhere. When defending a perimeter, you design with the three D's in mind: 1) Delay. Slow them down, break up their momentum (they being the invader, of course!) and separate them if you can. 2) Destroy. Kill them, eliminate them for acting or neutralize their movement or ability to harm. This could be done in a lot of ways, not the least of which is using up their ammo (resources, in this case. Use all the mage's spells, all the party's healing, etc.). 3) Denude. Strip the enemy of their capacity for harm. This is where you target their equipment or capability. Inflict a wound on one so others have to carry or leave him behind, that kind of thinking. Add in destruction of weapons, armors, and resources and you get the thought. Its also the whimsical: change their gender, turn their armor to lead, and so on.
DH employed all these ideas if you give his dungeons a once over. On the surface they look chaotic. Its the point. Of course, they also didn't always fit the idea that sat behind but that's a different discussion. Caliban is my favorite to point out on that topic. I'll save it for tomorrow.