Engineering principles for better fantasy worlds, cities, and dungeons.
Dec. 06, 2025
Tags: GameMaster, Dungeons
This is part 3 of a 3-part series about designing dungeons and underground structures in accordance with real-world conditions. This part provides practical advice for Game Masters and worldbuilders in using underground structures. To explore the structural integrity of such structures, see Part 1 here. To explore the layout and effects of water on such structures, see Part 2 here.
IX. Construction Tells a Story
Once a dungeon obeys structural logic, it stops being just a backdrop and starts becoming a historical record. Every support, crack, reinforcement, and collapse is evidence of decisions made by builders who were responding to real constraints. When you treat a dungeon as something that was constructed rather than simply placed, its story begins to emerge naturally from the stone.
Structural inconsistencies are often the most revealing clues. A narrow, carefully supported corridor opening into a vast, rough-hewn chamber suggests expansion beyond the original plan. A newer tunnel cutting awkwardly through older masonry implies urgency or desperation. Reinforced chokepoints hint at areas that were once vulnerable—or once important enough to protect at all costs. None of this needs explicit explanation; the structure itself does the work.
Repairs are especially powerful storytelling tools. A cracked arch held together by metal bands or wooden braces tells a story of decline and improvisation. A collapsed section that has been sealed rather than rebuilt suggests that resources were scarce or the area was no longer worth saving. In contrast, pristine supports in a sea of decay imply selective maintenance and intentional prioritization.
Even the absence of structure can be meaningful. An area left dangerously unstable might indicate it was abandoned suddenly, avoided deliberately, or used only briefly. A natural cavern incorporated into the dungeon with minimal modification suggests builders adapting to what they found rather than imposing a rigid plan. Each choice reflects values, capabilities, and circumstances.
Reading a dungeon like an archaeological site also allows you to layer time. The oldest sections might follow different engineering logic than newer ones. Early builders may have been cautious, staying close to the surface and using heavy supports. Later expansions might push deeper or wider, relying on better techniques—or taking greater risks. Collapses and reinforcements mark the boundaries between these eras.
When construction tells the story, exposition becomes optional. Players and readers don’t need a lore dump to understand that something went wrong here; they can see it in the sagging ceiling and the hurriedly shored-up wall. The dungeon feels real because it reflects the same truth as all enduring structures: it is a compromise between ambition and the limits of the world that contains it.
X. Common Dungeon Tropes (and How to Fix Them)
Many classic dungeon tropes exist because they are familiar and easy to map, not because they make structural sense. The good news is that most of them don’t need to be discarded—just adjusted so they feel grounded rather than arbitrary. Small changes informed by engineering logic can preserve the fantasy while improving believability.
The giant underground throne room is a frequent offender. A vast, rectangular chamber with a flat ceiling is one of the least stable forms imaginable. To fix it, make the space partially natural, carved into a massive cavern where the surrounding rock is visibly thick. Alternatively, break the room up with colossal arches, clustered pillars, or stepped terraces that reduce span lengths. A partially collapsed ceiling can also reinforce the room’s age and danger without sacrificing scale.
Endless right-angle corridors are another holdover from grid-based design. In reality, long straight tunnels concentrate stress and offer little resistance to lateral pressure. Curving corridors, slight offsets, and segmented passageways are far more stable and far more interesting to explore. Even a gentle bend every so often suggests builders responding to geology rather than drafting lines on a map.
Perfectly preserved ruins strain credibility unless there is a strong reason for their condition. Time, water, and neglect leave marks. To fix this, decide what has failed and what has survived. Maybe the stonework remains intact but wooden elements are gone. Maybe upper levels are stable while lower ones are flooded. Selective decay feels more realistic than universal ruin or eternal perfection.
Bottomless pits are dramatic but rarely plausible. Instead of infinite drops, consider sloped failure cones filled with rubble, partially flooded shafts where depth is hidden, or collapsed vertical passages that descend farther than anyone can safely see. These alternatives preserve the sense of danger while grounding it in physical reality.
Uniform construction throughout the dungeon flattens its history. Real structures change over time as techniques, materials, and priorities shift. To fix this, let different areas follow different rules. One wing might be heavily supported and orderly, another narrow and improvised, another overtaken by natural caverns. Variation signals age, adaptation, and conflict.
By reframing these tropes through a structural lens, you don’t lose the fantasy—you sharpen it. The dungeon becomes stranger and more compelling precisely because it feels constrained by real forces. When the environment itself seems to resist its own existence, every classic element gains weight, danger, and narrative depth.
XI. Practical Checklist for Dungeon Designers
Once you start thinking structurally, it’s easy to overcomplicate things. The goal isn’t to turn dungeon design into an engineering exam—it’s to give yourself a quick set of questions that catch problems early and spark better ideas. This checklist is meant to be used fast, at the sketch or outline stage, before you get lost in room details.
Start with the most important question: what is holding the ceiling up?
If the answer isn’t immediately obvious, the space probably needs arches, pillars, thicker walls, or a smaller span. Large rooms should have large, visible structural solutions. Small spaces can rely on surrounding rock, but they should feel appropriately enclosed.
Next, ask where does the weight go?
Think vertically and laterally. Weight should move down into solid ground or thick walls, not disappear into thin floors or unsupported voids. If you have stacked rooms or multiple levels, make sure one level’s floor isn’t another level’s miracle ceiling.
Then ask where does the water go?
Is the floor sloped? Are there channels, sumps, or flooded sections? If the dungeon is old, decide what failed first. If it’s still occupied, decide who maintains the drainage—and what happens when they stop.
Follow that with how was this space excavated?
Wide, smooth chambers imply time, skill, and resources. Narrow, irregular tunnels suggest hand tools, urgency, or poor conditions. Vertical shafts should have a reason. Ramps and spirals should feel intentional rather than decorative.
Another key question is why hasn’t it collapsed yet?
Is it carved into strong bedrock? Actively maintained? Magically reinforced? Recently built? If the answer is “it just hasn’t,” that’s a sign the design needs another pass.
Finally, ask who built this, and who kept it alive?
Structural choices reflect culture and priorities. Careful, redundant supports suggest cautious builders. Risky spans and rushed reinforcements suggest desperation. Areas left unstable or sealed off tell you where the builders gave up.
You don’t need to answer every question in detail. Often, a single strong answer will resolve several issues at once. The purpose of this checklist is not realism for its own sake, but coherence. When a dungeon’s structure makes sense, the space feels intentional—and intention is what turns a collection of rooms into a place worth exploring.
XII. Conclusion: Constraints Create Better Fantasy
It’s tempting to think that realism and fantasy are at odds—that paying attention to engineering somehow dulls the magic. In practice, the opposite is true. Constraints don’t limit imagination; they give it something to push against. When dungeons are shaped by gravity, water, material limits, and time, they feel heavier, older, and far more dangerous than any collection of arbitrarily placed rooms.
Structurally sensible dungeons gain texture automatically. Collapses aren’t random; they happen where support failed. Narrow passages exist because wide ones were too risky. Flooded levels tell you exactly when maintenance stopped. Even without monsters or traps, the environment itself communicates risk. Players and readers feel it instinctively, because the dungeon behaves the way real places do—by resisting its own survival.
This approach also makes worldbuilding more efficient. Instead of inventing lore to justify every feature, you let the structure speak. Arches, pillars, drainage channels, and patched repairs tell stories of ambition, adaptation, and decline without a single paragraph of exposition. The dungeon becomes a historical artifact rather than a stage set.
Perhaps most importantly, engineering principles scale. The same ideas that make a dungeon believable apply to underground cities, fortresses, mines, and even surface architecture. Once you start thinking in terms of load paths, materials, and failure modes, your entire world gains internal consistency almost by accident.
You don’t need to be an engineer to design better fantasy spaces. You just need to respect the fact that empty space underground is a victory wrestled from an uncaring world—and that victory is always temporary. Build your dungeons as if they had to survive, and they will feel alive long after the map is finished.