Engineering principles for better fantasy worlds, cities, and dungeons.
Dec. 09, 2025
Tags: GameMaster, Cities
This is part 1 of a 2-part series on making realistic cities with the One-Hour Rule. This entry focuses on the principles behind the rule. For the second part, which provides applications and steps for utilizing the One-Hour Rule, see Part 2 here.
I. Introduction: Why Cities Feel “Off” in Fantasy
Most fantasy cities work in the sense that they have names, districts, and a list of interesting locations—but many of them don’t feel real. Streets exist because the map needed to be filled. Neighborhoods are divided by theme rather than purpose. A blacksmith lives next to a palace, a tannery sits upwind of noble estates, and somehow everyone can cross the city in minutes no matter how large it’s supposed to be.
The problem usually isn’t a lack of creativity. It’s that cities are often designed as collections of cool ideas rather than as systems shaped by daily human needs. Real cities, especially pre-industrial ones, are constrained by time, effort, and access. People had to walk to work, haul goods by hand or animal, and get food, water, and safety without modern infrastructure. Those constraints quietly but powerfully determined where things could exist.
The good news is that you don’t need a degree in urban planning to fix this. You just need one simple question: how far can someone reasonably travel in an hour? When you design a city around time instead of arbitrary distance, the layout starts to make sense almost automatically. Markets cluster where people can reach them. Power gathers near transportation hubs. Poorer districts end up farther from convenience—not because the author decided so, but because that’s how cities grow.
This article introduces the One-Hour City, a fast, engineering-inspired framework for building believable fantasy cities with minimal effort. By grounding your worldbuilding in how people actually move through space, you can create cities that feel lived-in, logical, and rich with story hooks—without spending weeks on maps no one will ever see.
II. The Core Principle: Time, Not Distance
When we imagine cities on a map, it’s tempting to think in terms of miles, walls, or population numbers. Real people, however, don’t experience cities as distances—they experience them as time. How long it takes to get to work, to market, to the temple, or to safety matters far more than how far away those places technically are.
In a pre-industrial setting, time is an unforgiving constraint. Most people walk. Goods move at the speed of an animal, a cart, or a human back. Roads are uneven, crowded, muddy, or steep. Every additional minute of travel has a real cost in fatigue, productivity, and risk. As a result, cities naturally compress themselves around what can be reached in a reasonable amount of time.
As a rough but usable baseline:
These numbers don’t need to be exact to be useful. Their purpose is to anchor your intuition. If a baker must walk an hour each way to get flour, that bakery won’t survive. If guards need more than an hour to reach a disturbance, authority weakens. If food can’t arrive quickly, neighborhoods shrink or starve.
This is why rivers, ports, and major roads are so dominant in real cities. Water transport collapses time and effort in a way land travel never can. A city with a navigable river effectively cheats the one-hour limit for trade, while still obeying it for daily life. Entire districts exist where they do because moving something that way was faster.
For worldbuilding, this shift—from distance to time—is incredibly powerful. You stop asking “how big is the city?” and start asking “what can a person reasonably reach in an hour?” Once you do, city size, density, and layout begin to answer themselves, and the city starts to feel coherent without you needing to justify every street by hand.
III. The One-Hour Rule Explained
The One-Hour Rule is simple: in a functional city, most people must be able to reach the places they rely on every day within about one hour of travel from their home. This isn’t a law written down anywhere, but an emergent limit imposed by human endurance, daylight, and economics—especially in pre-industrial societies.
Daily necessities cluster tightly. Food markets, wells, places of worship, workplaces, and local authority all need to be close enough that a person can reach them, conduct their business, and return home without losing most of the day. Once travel time exceeds that threshold, costs compound: fatigue rises, productivity drops, goods spoil, and safety decreases. Neighborhoods that fall outside the one-hour bubble either become self-sufficient, specialized, or poor.
Historically, this is why many medieval cities feel surprisingly compact on maps. Even large cities were dense, noisy, and vertically stacked with activity. Walls often enclosed only what could be reasonably defended and accessed within a short time. Beyond those walls lay fields, workshops, cemeteries, and satellite villages—places that didn’t need constant daily access.
The One-Hour Rule also explains social stratification without extra exposition. Wealthier residents buy time by living closer to markets, ports, and power. Poorer residents spend more time traveling—walking farther for work, water, or safety. This isn’t a moral decision by the city; it’s an economic consequence of limited mobility.
For fast city design, the rule gives you an immediate boundary. If most of your city’s population can’t reach food, work, or authority within an hour, the settlement either breaks apart, decentralizes, or changes form. By treating that one-hour radius as your city’s functional core, you gain a clear, realistic framework for deciding what goes where—and just as importantly, what doesn’t.
IV. Starting Point: Anchor the City
Every believable city starts with a reason to exist. Before it has districts, walls, or a name anyone remembers, it has an anchor—the thing that made people settle here instead of somewhere else. If you choose this anchor first, much of the city’s layout and power structure will follow naturally.
Common anchors include trade crossroads, river crossings, natural harbors, fortresses, mines, or religious sites. Each one creates different pressures. A river crossing pulls roads toward a single bridge. A harbor stretches the city along the waterfront. A fortress concentrates authority and protection in one place, while a holy site draws pilgrims and services that cater to them. The anchor is not just a landmark; it is the city’s original economic engine.
Once the anchor exists, early growth clusters tightly around it. People want to live close to the source of safety, wealth, or spiritual authority. Markets form where traffic is densest. Taverns and inns appear along the routes leading in. Administration and elite residences gravitate toward whatever controls the anchor—whether that’s a bridge, a port, or a keep.
This early core often defines the “old city” forever. Streets are narrow and irregular, buildings are layered on top of older ones, and property is expensive. Even as the city grows beyond it, this anchored center remains the place where power, tradition, and resentment accumulate. Newer districts may be cleaner or better planned, but they orbit the original heart rather than replacing it.
For rapid worldbuilding, anchoring the city gives you an immediate focal point. Place the anchor, then imagine one hour of foot traffic radiating outward. Where people need to be close, they crowd in. Where they can afford to be farther away, they spread out. With that single decision, your city stops being a blank canvas and starts being a system with history baked in.
V. Districts by Function, Not Aesthetics
Once you’ve anchored your city and established the one-hour core, the next step is to organize it by function rather than by random flavor. Real cities grow organically around what people do, not how pretty or thematic the streets look. Understanding this helps your fantasy city feel alive without hours of overthinking.
Typical functional districts include:
Even in small cities, districts overlap and blend naturally. A market may host residential spaces above shops; a guildhall may double as a temple or council hall. These overlaps are realistic—they reflect multi-use spaces in history’s cities where every square foot carried multiple functions.
Environmental factors shape these functional clusters as well. Wind direction affects where smelly trades appear. Flood-prone areas favor storage or industrial use. Traffic patterns dictate where commerce thrives. By letting practical concerns drive your city’s organization, streets, neighborhoods, and walls start to make sense intuitively, and your worldbuilding gains depth without extra effort.
In short: design around needs, not aesthetics. Function explains layout, and layout makes the city feel alive—even before you add color, flags, or magic.
VI. Transportation Shapes Everything
Transportation is the invisible skeleton of any city. Roads, rivers, canals, and gates are not just infrastructure—they are the forces that shape where people live, work, and gather. A city’s layout often makes more sense when viewed as a network of movement rather than a set of disconnected buildings.
Roads and streets dictate density. Narrow alleys limit carts, forcing neighborhoods to remain compact. Wide avenues invite trade, parades, and wealthier residences. Roads radiating from the anchor naturally become commercial arteries, lined with shops, inns, and warehouses.
Rivers and canals are even more influential. Water moves goods faster and in larger quantities than any cart, so neighborhoods cluster along navigable channels. A riverside market can support far more trade than one deep in the interior. Bridges and locks become choke points that concentrate foot traffic and create natural sites for walls, gates, or tolls.
Choke points aren’t just convenient—they’re inevitable. A single bridge or city gate creates tension and opportunity: taxes, trade control, or defense. Market squares often arise at intersections or bottlenecks, because commerce flows where people must pass. Military and civic authorities exploit the same constraints, placing watchtowers or administrative buildings strategically.
Transportation also explains social geography. Wealthier citizens live closer to major roads or waterways, reducing travel time and risk. Poorer residents occupy areas that are slower to reach or farther from safe routes. This isn’t arbitrary—it’s a pattern seen in nearly every pre-industrial city and gives your fantasy world instant plausibility.
By thinking about your city as a network of movement, you gain a natural guide for where districts form, where commerce thrives, and where tension builds. Streets, bridges, and canals become storytelling tools, not just lines on a map. A city designed around how people move is immediately more believable, coherent, and ready for adventure.
VII. Growth Over Time: How Cities Break the Rule
Even the most carefully planned city eventually outgrows its original one-hour core. As populations swell, trade expands, and technology improves, cities inevitably face pressures that push beyond the limits of daily travel.
When a city exceeds the one-hour radius, it solves the problem in a few predictable ways:
This growth naturally produces tension and character. Old city residents often resist change, clinging to traditions and older infrastructure. New districts may feel more modern, spacious, or orderly, but also less connected to the city’s heart. Travel time itself becomes a source of social and economic inequality: those who can afford transport, magic, or shortcuts retain access, while others adapt to peripheral living.
For fantasy worldbuilding, these dynamics are gold. They provide immediate story hooks: political friction between districts, challenges in defense, trade bottlenecks, or smuggling routes. By letting your city expand naturally around the one-hour rule, you create a setting that feels historically layered and functionally believable—without needing to micromanage every street, alley, or backwater.
VIII. Magic, Monsters, and Exceptions
Even in a world where magic exists, the one-hour rule remains surprisingly resilient. Magic can speed travel, move goods instantly, or defend a city from afar—but it rarely eliminates the practical constraints that shape everyday life. Most residents still live, work, and trade as if magic is limited, expensive, or risky.
Magic as a modifier, not a replacement:
Monsters and hazards also play a role. Dangerous wildlife, undead patrols, or roaming bandits make certain routes slower, riskier, or effectively unusable. Cities often develop around safe corridors, walls, or guarded bridges, reinforcing the one-hour principle even in a fantastical setting.
In other words, magic and monsters add flavor and complexity—they bend the rules, but they don’t erase the underlying logic. A teleportation circle might make a noble’s estate accessible in minutes, but the baker still needs flour delivered daily by cart. A dragon may make one bridge too dangerous to cross, but the marketplace persists elsewhere. These constraints preserve believability while giving you creative freedom.
By acknowledging exceptions without abandoning the core principle, you keep your city grounded. Magic and monsters become tools for storytelling and tension, rather than excuses for arbitrary layouts. The one-hour city remains your foundation, with fantastical elements layered on top for intrigue and spectacle.