The Architect DM: Structural Dungeon Design

Back in one of my earliest Architect DM posts I said that structure was one of the most overlooked elements of dungeon design. These days most of the published dungeon maps that I see are not bad with regards to structure, but from what I’ve heard this is still something that a lot of people would like to learn about for their personal, hand drawn dungeon designs.

In the first post I did about this topic (The Architect DM: Give It Some Structure) I started with the classic 10 foot by 10 foot room and expanded from there. Today, I’m going to start with the other classic element of D&D dungeon design – the corridor. Just as I expanded to a 20 x 20 room with 10 foot corridors in my previous example, I’m going to use 10 foot wide corridors for my illustrations because I believe it makes them easier to read. I’m fine with this because all of the design elements I’m going to discuss should be easily applicable no matter what width corridors you’re using.

Bland & Reliable

Your classic dungeon corridor (excluding caves, if you’d like to hear about those too please let me know) keeps going and going until it meets another corridor or dead ends in one of the gloriously deadly rooms you’ve designed. I’m calling these corridors bland and reliable because their lack of features makes them predictable in addition to boring, and there’s nothing worse than foreseeing your own boredom. Sure, you can throw in some oddly angled corridors, some secret doors, and a pit trap to make it less predictable but then you’re taking the design from reliable to completely random. If we’re assuming someone has created this dungeon (which we are, no caves, remember?) then very few elements are going to be truly random. Even pit traps, which you want to be completely unpredictable, as a trap should be placed in the best strategic location which in turn makes them more predictable to the wary trap-savvy rogue.

Now let’s look at some ways of making the classic dungeon corridor more interesting and more believable at the same time. If you’re underground, then the first basic concern is what’s holding the roof over your head. In most cases the walls are sufficient to hold up the roof of a corridor, but what if the corridor started to collapse at some point and has since been reinforced? Adding in regular, unobtrusive columns attacked to the walls at a regular interval helps break up the progress through the corridor and establishes a rhythm that you can then use to help in your dungeon design. This also adds another layer of “character” to your dungeon that tells the players this corridor may not be entirely stable as it’s already started to collapse and had to be reinforced once before. Perhaps my favorite result of adding something like this to your dungeon, much like adding columns into larger rooms, is that my players almost always consider if they can collapse part of the roof in by damaging the structure in a dire situation.

Whether or not the corridor is structurally sound, you don’t need a solid reason to add column elements along a corridor. Ancient civilizations loved carving things into stone, and it makes perfect sense that there would be a series of decorative columns placed along the walls of a dungeon hallway.

Design by Rhythm

One more great aspect of creating a rhythm in your dungeon is that this makes your job of designing the dungeon much easier. Once you’ve established a size module for the dungeon, it becomes easier to place things within it. If you go back and look at the featureless corridor above, then imagine it stretching the length of your dungeon design and think about where you would place a door or connect a hallway. The odds are you either picked randomly or chose a specific proportion (middle of the corridor, 1/4 of the way up the corridor) to place these elements. Now look at this corridor and think about where you might put a door/hallway coming off of it.

You may not have made the same decision as me, but I’d be willing to bet you aren’t that surprised by where I put the connecting hallway:

In fact, this kind of design element helps alleviate one of my biggest pet peeves in classic dungeons – the secret door. My experiences have been that in any given situation D&D players either don’t worry about searching for secret doors, obsess over searching for them at the expense of everything else, or pick up on some hint from the DM / location description and then search. I’ve run many published dungeons where several secret doors were passed by and wondered to myself what the purpose of having them in the design is.

Do they reward the party that searches every single inch of a dungeon? It’s almost a given that they will find the secret door if they’re taking that much time, and I don’t find much satisfaction in a sure thing. Do they reward the absolutely whimsical, random impulse searching? No matter what the real intent is, I enjoy this kind of design because it provides very clear delineations that players may pick up on and start to think, “Hey, this looks like a place a door might be…”

 The Better to Break It

By this point I’m sure some of you are thinking, “But I don’t want to make my dungeon so regular, so predictable, or have a rhythm to it.” My response is that adding these elements and creating a rhythm in your dungeon is still very helpful with these design goals. Adding a rhythm makes it much easier, clearer, and in my opinion overall better when you want to add elements that break that rhythm. If you want your dungeon to be unpredictable or more random, add a regular element to a corridor and then purposefully at some point take it away. The players will most likely notice, and you’ve added a small dungeon-centric mystery for them to investigate. Not to mention that doing this is ready-made adventure planning for you as you have to figure out why the design changed and what it means for the dungeon and for the adventuring party that’s exploring this location.

Here’s a bit of a disconnected but still very relevant example. Think about the early exploration scenes in the movie Aliens and not only how the characters’ experiences change but also the viewer’s experience changes. The marines go from a very rigid, industrial environment as they’re exploring the terraform reactor to the biological, unpredictable, and very fluid environment of the alien hive. The great thing about this shift in environment is that at first there are no aliens even present, it’s simply a change in the “dungeon” environment that evokes all kinds of feelings in the characters and viewers. You can achieve some of the same effects by setting up a rhythm in your dungeons and then breaking that rhythm in fun and interesting ways.

Further Down the Corridor

Obviously this post has only addressed corridors/hallways, and even then just a small selection of ideas for improving on them. My goal is to keep talking about structure in RPG dungeons until I cover everything I can think of to cover it. Here’s where you can help! Do you have questions after reading this post? Do you have other ideas of how to do things, or elements of your own dungeons you’d like help with? Please get your questions, concerns, and ideas to me either in a comment here, on twitter (@Bartoneus), or e-mail me at the address in my signature below this post. I want to hear from you, but more importantly I want to know what you need help with when you design your own dungeons!

Click here for the rest of the Architect DM Series.


  1. secret doors might seem less pointless when you realize that certain races had a chance to detect them automatically, without looking, meaning the DM rolled to check. there was a distinction between hidden and concealed doors, as well as an increased chance if the PC was actively looking, but some races could detect them “passively”, which is in effect a “reward” based on their race. so for example in my b/x game, the elf noticed one as it passed by, based on my (hidden) roll, and it was cool bc it made the elf seem alien. my only point is, in old-school editions, PCs dont always need to be constantly searching for them. old-school racial flavor is a good thing imo, but it is true that you usually wouldnt want to make the discovery of a hidden door be a required part of an adventure

  2. Nice article and excellent advice.

    I agree with your assessment that secret doors can be perplexing. Ultimately, the DM wants his secret doors to be found. Otherwise, he wouldn’t bother placing anything behind them. Some clue should make players suspect that a secret door exists, like a big empty space on the map, a dead-end corridor with no purpose, a trap in a seemingly pointless location, or a blizzard of decoration where most of the walls are blank. I think the biggest thing that’s been lost from the “secret door economy” is the time element. It used to take a character 10 minutes to search a 10-foot section of wall for secret doors; finding them was essentially automatic, if you took the time to search. But during that time, the DM would roll for wandering monsters, and they were always bad. Wanderers tend to be tough, to gain surprise, and to have very little treasure in return for the precious hit points and spells lost defeating them.

  3. This is one of my pet peeves, your dungeon: being game-ism versus simulationism. I actually (try to) do both. First build your dungeon logically, if you have set pieces build them around it: if you want a fight on a bridge over lava, why is that lave there (it’s the power source) why is there a bridge over it (the central power room needs to be in the center of the lava lake). Then work from there out. (guards would be placed where, workers where, storage, etc,.. then connect it all and give a logical entrance.
    Think of secret doors less as actual secret doors but more as shortcuts (a ventilation shaft that bypasses a checkpoint for those that want to use it). And being able to place more logical features there like this article postulates will help make them even more realistic (without losing sight of the game).

  4. Gargs454 says:

    The problem I have with secret doors is that it seems there’s always somebody who has such a high passive perception that he’ll automatically see them anyway. Perhaps its just my players who have always taken the approach that perception (or spot in the old days) was the most important skill, and others may have different experiences. That being said, while I rarely “conceal” a secret door (meaning I’ll just mark it on the map anyway), I do think that there can be value to the secret door. It gives the dungeon personality. It gives the villains personality too (or at least whoever created the door).

    All that being said, another great article. What I like about this series is that it is often the little things (like the columns on the walls) that may not change the mechanical aspects of the game much, but which will absolutely breathe more life into your world. The columns as drawn probably are not big enough to even grant partial cover (though in dim light can maybe help a character hide). However, they do show that somebody was there once, and that somebody cared. Whether it was caring about pumping up their ego (the columns are really statues of the Sheriff of Nottingham) or simply cared about making the structure sound (they were added later, some of the ceiling pieces appear newer, etc.).

    @Lord Byte: I too like to use that approach. I find that at times I struggle with combining the classic dungeon crawl with the realism. I don’t want all of my dungeons to be drawn out dungeon crawls of course, but there’s still something about crawls that is just plain fun (maybe I’m just too old :p). That being said, I’ve found that the larger the dungeon becomes, the less sense it starts to make to me. It might start with a great idea or concept, but by the end there’s just a lot of filler. Part of this is a result of not having enough time to prepare (and I end up drawing dungeons on the fly) but part of it is also just a lack of focus on my part (hurrying up to get the battle set up). Perhaps one of these days I’ll win the lottery and then have plenty of time to prepare. 😀

  5. Philo Pharynx says:

    As for the “why” of secret doors, there’s lots of reasons – escape tunnels, ways to covertly meet lovers, servant entrances, places to keep hidden bodyguards, places to stash riches against ordinary (i.e. non-PC) thieves, ways to avoid dealing with deathtraps.

    As for elves automatically searching for secret doors, make a few secret doors that just open onto elf-seeking traps. Or have secret doos hidden by illusions. Elves don’t get automatic chances to see through illusions.


  1. […] do you design dungeons? Straight line corridors? Bland rooms? Bartoneus @ Critical Hits offers some different options that are brilliant and I wish I’d thought of […]