9 nearly full pages of old-school mega-mega-mega-dungeon.
All created using the random tables on pages 170-172 of the AD&D 1st Edition Dungeon Masters Guide by Gary Gygax, published in 1979.
Why? Because drawing dungeons from just the scratch of my imagination has become kinda boring.
I marked my entry point in the center of a page and simply went with whatever happened. It was linear at first, but it soon expanded; side passages upon side passages, straight, diagonal, parallel, intersections -- 4-ways, Xs, Ys, Ts, all leading to chambers and rooms of all shapes and sizes (it's implied but never explicitly stated that rooms have doors and chambers do not). These tables are designed to go on and on and on; there are occasional dead-ends, but if you don't consciously stop it, it probably will not stop (25% of periodic-checks introduce side passages and 50% of side passages introduce multiple side passages).
I wanted every passage to take you deeper down the rabbit-hole, so no looping was allowed until deeply forward for every path. Every new corridor goes underneath any room or passage it crosses, but eventually loops do occur, plenty of them. At times, it's like solving a puzzle; decisions have to made, to connect or not connect? Sometimes I beg for a dead-end and sometimes I have no choice but to place one and sometimes a loop is allowed. This place is wild. I get lost just looking at it. If players were mapping it, they'd fuck up quickly, just as they would if it were a real place.
This process also reinforces the notion of space; not every room will be occupied (could/should still be interesting though) and there are many long, twisting corridors. Noise wouldn't travel here very well, not clearly. Certainly you might hear echoes and clangs and screams, but they would haunt like distant nightmares. It's easy to see adventurers snooping about, even fighting, without disturbing much of anything at all. What about the goblins in the next room? With Gygax's system, chances are, there are no goblins in the next room.
Eventually I came to the edge of the first page, all four edges, and thought, what the hell, let's keep going, and before long, it became clear that it would bleed over onto at least 9 pages. I configured entry points to align with Act III if I insanely go in that direction. Who am I kidding...
Some thoughts...
Wandering Monsters are built in. That's right, on the main d20 "Periodic Check Table" a roll of 20 results in a wandering monster, not a check, an actual random monster right then and there. So, I put an X on the map, always in a corridor. Sometimes they occur in bunches. So, what if wandering monsters were always handled this way, and, is that a repeated occurrence or just a one time thing? Just thinking out loud; one time occurrence is obvious to me, unless something (a glyph?) is spawning creatures.
Stairs... come up plenty of times, but there's no way I'm doing levels below this monstrosity. So, I simply put stairs in the corridor -- almost always going down. Combined with the fact that new passages go under already drawn ones, the farther out you go, the deeper underground you are. It's shaped like an underground hill. This could be how danger (dungeon levels) is measured. Center page -- dungeon levels 1 and 2; 8 pages surrounding the center page -- dungeon levels 3 and 4; 16 pages surrounding that -- dungeon levels 5 and 6, etc. So danger equals distance from the center as opposed to levels straight down.
Tricks/Traps come up as often as stairs and such; all in corridors. I've never been a fan of hallway traps because they're punitive and make the game an unfun slog. The players have no defense other than to check every 10' of the place. So whatever these turn out to be, there must be clues.
Special passageways... Rivers, caverns, chasms, streams, all come up periodically, but I've avoided all so far. I have a certain look in mind -- the cellar of Castle Dracula, complete with arched columns, vaulted ceilings, and at times, unfinished floors. I may add subterranean canals at some point, but I'll be damned if I taint this place with caverns.
These are not like modern doors.
No knob to turn.
No door handle.
Often, the outside has a keyhole and nothing else.
Maybe an iron loop or rung to grab, but these are most likely used to pull the door shut when leaving; may double as knockers.
Hinges are on the inside.
They almost always open inward.
On the inside are often multiple locking mechanisms beyond a possible keyhole: Latches that slide sideways, latches that slide into the floor and ceiling. Rungs for wooden beams to slide into.
They are solid as fuck.
You are not hacking through these doors with your weapons.
It takes one full 10 minute turn per attempt to pick the lock which may include multiple latches and such. Two turns if a non-thief is somehow attempting. (My rule).
It could take one full turn before that to search for traps... or you could say that is part of the picking process, but still, two rolls, three, if you find and need to remove prior to picking. Whatever, one turn minimum for the whole process.
One full turn per attempt to open a stuck or heavy door.
Looking at the doors below, bashing them down seems ludicrous in many cases and of course should result in a mandatory and heightened wandering monster check.
It's hard to imagine hearing anything through them... that's why it's a special thief ability. And you're putting your ear to where the door meets the floor, not up against the door itself like you're trying to crack a safe. (Maybe while picking).
Attempting any of the above forfeits any hope of surprise. In fact, it should guarantee surprise against the PCs.
Simply opening the door should forfeit surprise. Imagine the noise.
Doors are obstacles.
More flavor... How did you find the spell? (Roll this before you roll for the spell, as it might influence whether or not you choose to learn it).
And just like that, Wizards are infinitely more interesting.