Actual Dungeon Design

With Issue 2 being the first to feature an actual dungeon level (Level 1 is in layouts/waiting for one more article to complete), I've decided to put to pap... blog a few overview features to remember when designing each level.

In no particular order:

The dungeon is an ecology, not a series of encounters:
That means the dungeon, especially if a group lives there, needs to have everything a habitat would have; sleeping quarters, bathrooms, a place to eat, etc. Obviously these things might be different then "friendly races" standards because of the unique ecology of the race that inhabits it, but it should all be there. Some rooms may be empty, some not particularly thrilling (storage with no secret doors or coins), but all should make sense.
This also means that when stocking a dungeon, stock it to make sense, not always balanced. There may be "tougher" monsters in higher levels, players should know when to run, but only if it makes sense. You could put an 8HD Green Dragon on Level 2 but why wouldn't that dragon take out the inhabitants of that level and take over? So he can't be there. Look to place monsters that make sense within the dungeon you're making, not the "balance of the game."

Each level should stand alone, yet connect to the whole:
I've mentioned this before. Each level should be able to be played as a stand alone dungeon if that were someone's desire. Each level should have a goal, an "end boss" to beat, and a sense of accomplishment once finished. However, there should also be elements that connect each level to the mega-dungeons overall plot, an item here, a few clues there, etc. If run alone, these items, clues would, in essence, never be "solved," but many stand alone dungeons (especially earlier editions) had elements that really only the DM knew about because of reading the Backstory.
Because of this rule, each level should have several "set pieces," areas more exciting then the hallway with a few orcs or the prison cells with the torturer. There should be something that the players talk about after the game is over, whether by architectural design that makes for a memorable (and not just "I stand in front of him and swing my sword) combat round, a fiendish puzzle that was solved with player skill, or a reoccurring NPC that causes nothing but trouble for the PCs and finally gets his later in the dungeon.
Again, because each level stands alone, there should be a reason to be in there besides trying to get to the next level. Each should have a plot hook designed to make the PCs (assuming they're proper heroes) want to explore the dungeon and reach the endgame, instead of bypassing it quickly to get to the next level or just killing/exploring everything to level up.

Each level should allow a party of four to, potentially, level up
When stocking the dungeon, each level should have enough treasure and enemies to let an average party of 4 characters to level up. I chose 4 because, while older dungeons tend to talk about parties 6-8, 4 seems closer to the group size now a days. This is an easy formula to figure out. Take the average XP it takes from all the classes in LL to go from the current level of the dungeon to the next level and multiply by 4. So, for instance, if I was designing level 3, I'd take the difference from level 3 to 4 for each class and average them (about 4107 XP) then multiply that by 4 (16428) and then make sure there's enough monsters and treasure to hit that mark. Note, don't include random enocounters or monsters that are purposely supposed to be avoided. You also may want to add a little bit more, to cover the fact that a party may not find every hidden treasure cache or decide to fight every monster that they wander into. The game self balances with classes that have more powers at lower levels (slower leveling charts) and larger parties (they may not level, but their higher numbers make for ease of play.)
Also, remember when adding monsters to not just account for HD, but also No. Enc. An encounter of a creatures HD is balanced with the average of the No. Enc. A single 1 HD monster is not a balanced fight against a 1st level party (unless it's No. Enc. is 1-1).

Remember the 5 senses
Since we're using the 5 senses system to describe the dungeon, when creating it, think in all 5 senses. What do you hear in the room, what does it smell like, does anything have a unique texture? Remember to think of things a certain race (or class) may know that others don't, certain underground structures for dwarves, flora of fey origins for elves, the skill level of a locksmith to construct a particularly locked door for a thief, etc. Don't just rely on sight based descriptions when designing a room, think of how you, yourself, would perceive an area, with all 5 senses.