The Architect DM: Open Spaces Design Toolbox

As I introduced in my last post about improvisation, I believe that the key to being able to design a location (whether beforehand or on the fly) is grounded in what I’m calling your toolbox for design. The key is that once you have a well developed toolbox to pull ideas from, you can more readily and quickly design a location for your tabletop Roleplaying Games on the spot or adapt your planned locations to fit the developing needs of the game table. An underlying goal of this series of posts is to help you develop the toolbox required so that you will be able to accomplish this task with relative ease and a good amount of confidence.

I’m going to start by discussing the open spaces that come into play in your average D&D game. The locations I’ll cover in this post will include streets, plazas, and markets but should be adaptable to a larger variety of spaces if you apply the pieces correctly. I started some discussion on open spaces in my post about incorporating them and the larger concept of holidays into your games, but today I’m going to focus more on the specifics of the design process.

Starting in the Streets

Let’s assume that you’re planning a street ambush, inner-city brawl, or an encounter that involves the party protecting (or assaulting) a caravan and you find yourself in need of designing a street location. Your typical town or city street is going to be incredibly easy to design the basics of, but the details can be what really define it as a great location for your game. The first big concern to figure out is what kind of traffic your street handles, it can range from a larger alleyway that mostly sees foot traffic to a bustling medieval highway full of horse drawn wagons. More fantastic concerns may also come into play such as what a street might look like in a city built by giants or even smaller creatures like kobolds. This decision should also directly tell you what kinds of buildings will run along both sides of you street. I’m focusing more on the urban street concept right now, but if there is demand I can get into the specifics of rural roads and trade routes in a later post.

Once you’ve decided on some of the key factors mentioned above, designing a street on the fly should be relatively simple. If you’re running D&D you can quickly count off 10 feet (or 2 squares, whichever you prefer to use) for a cart path in the road and assume 5 ft. (1 square) on each side for general wiggle room and/or foot traffic. So for a one-way or single-cart street you would use roughly 20 ft. as your width, or if you want to do a two-way street you would have 30 ft. (10 ft. x 2 for carts, 5 ft. path/sidewalk on each side of the street). At this point you can decide to keep your street mostly straight or have it be a turn or whatever your heart desires, just make sure that any turns are of a gentle curve so that they’re believable for carts or your desired type of traffic to easily navigate the turns.

When adding boundaries to your streets with buildings, walls, vegetation, or whatever you choose to use the exactness of it is not very important. When I improvise a street setting I simply begin with one building right up against the street. To keep things simple you can start with just a small square building, and then from there you place building after building allowing for smaller alleys between all of them. As you do this, the variation is the key to improvising it. After you’ve drawn one or more buildings, change the shape to make them rectangular (either parallel to the street or perpendicular) and then start to throw in some L-shaped buildings or even a few less conventional shapes. The key here is keeping the functional nature of the buildings in mind with regards to your players.

Typically when I am designing a street I anticipate my players to use alleys and run around buildings, and often to get onto the roof of some of them, but rarely will they go into the buildings unless a monster or NPC does so first. There are certainly exceptions to this, but for the most part you are designing a street as the setting for your encounter and the buildings around it are simply boundaries and at the worst would only have one room that would be entered from the street before action was pulled back into the street again. The details that can really make a street encounter fun are the buildings that define the space and how they create a strong contrast between the expansion and contraction of space. When you’re out in the middle of the street you have a larger area to work with and when you’re in between or up against the buildings the action is going to be up close and fast paced. I mentioned getting onto the rooftops earlier because in almost every street setting that is going to be the most advantageous position for enemies to attack from (so put them there!) and it’s also a great way to incorporate skill checks and a little bit of hardcore parkour into your game. Everything’s better with hardcore parkour.

Into the Plaza

A plaza is traditionally a larger open space that is often found at the intersection of two or more streets, so the above advice ties into the surrounding areas and the scenery that will lead the action into a plaza. When you start to design a plaza, you will never (EVER) be wrong to start by placing a primary element of focus in the dead center of your location. Make it a fountain, statue, or even a whole building such as a court house, bell tower, or even a rickety old water tower. The central element is so important that it should actually be a conscious and meaningful decision if you decide not to incorporate one. From here we have a lot of the same considerations that we did for the design of a street such as what the plaza is typically used for and what kind of traffic it can support. If the same roads are leading into this plaza, then you can simply measure the distance of your street out in each direction from your central element and BAM, you have a plaza.

Unlike the design of a street though, your plaza should have a variety of interesting terrain within it that divides the space into smaller portions. Stairs are a great element to use in a different application then most gamers are familiar with in their typical dungeon setting. The stairs that you will find in a larger plaza are much shorter in height but longer in tread, and you will often find them in groups of only 1-3 stairs at a time. Perhaps the bell tower in the center of your plaza has a 10 ft. wide stone foundation that it sites on which has two or three stairs leading up to it in a handful of locations, or you could have the entire perimeter of the foundation be stairs. The key with using stairs in this situation is that they provide quick access up and down the tiers of your plaza, but any character (or monster) that can climb or jump won’t have to worry about them as much. In this way you can use short walls that lead to higher levels in conjunction with stairs to direct the action of the encounter by creating divides in the space.

Placing buildings around your plaza should happen in much the same way as with a street, except that often the buildings around a plaza will be much more public in nature. If your plaza is a bustling trade market then not only will it be filled with wagons and caravans (and may not have a central feature as the market itself is the main focus) but it may also be surrounded by shops in the lower levels of the buildings. As for the issue of filling up the rest of the space in your plaza, feel free to incorporate elements such as stopped wagons, tethered horses, or even a fenced off plaza tied into one of the nearby buildings (possibly a tavern with outdoor seating). Other common elements could be seating, fences, natural features such as bushes and trees, or low walls and shifts in elevation as discussed above. Also the same ideas mentioned for streets apply when it comes to using surrounding buildings, for the most part their interiors are not that important but their rooftops and the alleys they create can become a very interactive feature for your encounters.

The best analogy I can think of when it comes to this kind of design is thinking about setting up a table before playing a game of Warhammer – often we had a handful of specific terrain features that each player would then place on the table how we wished. The process should be much the same for you as the DM designing a plaza, and it can even be quite fun to throw a bunch of obstructing terrain around the plaza and then let the players decide which direction their characters enter the plaza from.

Now Get Out There and Design Me Some Cities

I realize this hasn’t been a fully comprehensive guide to pseudo-medieval fantasy city design, but for the most part this is a detailed account of the exact process I go through when running my D&D game and I encounter a situation where a street or urban plaza is required. If the messages aren’t coming across that clearly, I may go back and provide some helpful illustrations to go along with all of this, so please let me know if it’s not clear.

Aside from that, the biggest point I need to stress is to not be afraid of improvising this stuff in front of your players. Hell, you can even take suggestions from your players and adapt the location to fit their preparations if the mood strikes you. Once you’ve tried it a handful of times you’ll start to see how the players react and interact with what you’ve provided and you will only get better at doing it on the fly, and the best part is that you won’t have to worry all that much about what the locations look like as you’re planning out your game, and less time needed for planning is always a good thing.

Click here for the rest of the Architect DM Series.


  1. It’s the little things that make the biggest impact, such as how wide a street is, and why.

    As you also touched on, one of the best immersion tools is for the players to take the reigns from time to time, describing some of the scenery (especially during a fight or chase).

  2. Dixon Trimline says:

    I love the hands-on, real-life approach to the city design, how the component use would define dimensions. Thinking about buildings creating edges and creating outward from a central feature like a fountain or a statue, this really gets the ole creative juices flowing. Bravo + enthusiastic applause.

  3. I really like this series. It seems simple, but even just giving decent dimensions for the streets is pretty nice to have. My question I guess would be what would be decent dimensions for a standard medieval fantasy building? My guess, particularly when we start thinking about residences, is that the buildings in our games will almost have to be larger than they would have been in real life simply to give the PCs and monsters enough room to breathe. Still though, any thoughts would be most appreciated.

  4. Tourq: my favorite part is during chase or equivalent scenes, as you mention, when players take active control of designing the environment without even knowing it – “are there any carts around I can push in their way?” “are there any window ledges to grab onto?” – when they ask questions like this they are almost always aiding the DM in the design of the world in such a way that they rarely ever notice. That’s what I love and want to encourage!

    Dixon: Thanks! Hopefully we get another chance to game together in the near future so we can discuss such things in further detail.

    Gargs: Glad you’re enjoying it, and those are exactly the questions/suggestions I’m looking for. My next step in this line of posts is to discuss the specifics of some types of fantasy buildings, but to address some of your concern right now the answer is yes – you almost certainly want to design buildings, and their interiors, as much larger then they would have been in reality to allow for more motion and combat to take place comfortably inside of them. This is already done all over the place in D&D and other RPGs, a 10′ wide hallway is actually incredibly large and you rarely see it in most buildings today much less back in medieval times – but they’re all over the place in RPGs because it allows for a greater choice of movement and maneuverability.

  5. So helpful – I’d love to see more general concepts of city building, like what districts would be where, how streets are formed and why they end up where they are. That would be great.

    I appreciate this so much because my campaign is about to head into the city from a long spurt of wilderness adventures. It was perfect timing for me.

  6. Just wanted to say, I’ve been enjoying the series. Not much to add other than to nod in vigorous agreement on the point that often getting players to use the environment is to have the enemy use it first. Really, having enemies use something first is another mode of description, one that is easier for players to grasp as usable as opposed to window dressing. The same goes for improvising objects in the environment.


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