Sigil: The City of Doors

A Player-Facing Primer for Our West Marches Campaign

Sigil is the crossroads of everything—every world, every plane, every timeline. It is a paradox made livable: a city that sits at the “center” of the multiverse while simultaneously existing nowhere. Adventurers arrive here from impossible pasts, uncountable presents, and divergent futures. And from Sigil’s countless portals, they step into any moment a Dungeon Master can imagine.

If our campaign has a beating heart, it’s this place.

What Sigil Is

Sigil floats above the impossible Spire, a mountain so tall that no creature has ever reached its apex. The city itself is built inside a massive ring-shaped structure—a great stone torus. When you walk its streets, the city curves upward around you, and if you look directly overhead you can see the other side of Sigil arcing far above, shrouded in mist and industrial haze.

There is no sky.
No sun.
No stars.

Light brightens and fades in a daily cycle called peak and antipeak, but the glow isn’t sunlight. It’s simply… Sigil.

Gravity pulls toward the ground wherever you stand—even though that “ground” is part of a ring. Fog and smog drift through the streets. Weather rarely changes. It is a city that exists purely for function: a planar hub without natural season or celestial rhythm.

A City of Infinite Portals

Sigil’s defining feature is its portals. Every doorway, window, arch, grate, alley mouth, or bent piece of metal might be a portal. The catch? It needs the correct key—an object, a word, a memory, a gesture.

These portals lead everywhere, and in our campaign, every includes time:

• Past ages of dead worlds
• Futures that may never happen
• Alternate histories
• Divergent realities
• Lost timelines
• Mythic moments frozen, repeating, or broken

This is why adventurers in the City of Doors come from every imaginable background—and why DMs in our West Marches are free to place missions in literally any setting they find exciting.

You want a Viking raid one week and a dying star the next? Done.
A prehistoric jungle followed by a noir demiplane? Easy.
A 20th-level mythic war on Tuesday and a cozy halfling mystery on Thursday? Sigil doesn’t care.

Sigil exists so stories can go anywhere.

The City Itself

Inside Sigil’s ring, the city is a dense mosaic of architecture: steel spires next to crumbling gothic towers, planar bazaar tents pitched beside infernal stonework, celestial halls adjacent to smoky tenements. Everything is jammed together, built outward and upward until the city meets its own edge.

Those who climb the outer wall and step over the boundary do not reach the Outlands below—they simply vanish into random corners of the multiverse. Most never return.

Sigil doesn’t do “normal.” It does interesting.

Magic Works… Differently

Sigil is famously hard on planar magic. The Lady of Pain (the city’s silent ruler) enforces strict cosmic rules:

• You cannot teleport into or out of Sigil.
• You cannot open new planar gates.
• You cannot summon creatures from outside the city.
• Plane shift fails unless using permitted teleportation circles.

But inside Sigil, teleportation and extradimensional spaces work normally. Bags of holding, rope trick, and portable holes function as expected (with the city's quirks still in effect).

What does this mean for players?
Your abilities still work—they’re just subject to Sigil’s unique “physics.”

Who Lives Here

Sigil is the backstage of reality. Everyone shows up eventually:

• Celestials mingle with fiends.
• Archfey drink beside inevitables.
• Mortals of every species shop in markets run by genies, hags, or stranger things.
• Languages from across time and creation float through marketplaces.

Humans may have originated here. Many scholars insist Common was born in Sigil and spread outward.

Factions, philosophies, and political groups give the city its rhythm. They argue, cooperate, scheme, and maintain infrastructure—unless something big goes wrong. If cosmic danger threatens the city itself, the Lady of Pain intervenes.

No god can enter Sigil. None.

But their agents? Their cults? Their plots? Those slip through the doors constantly.

A DM’s Playground

Sigil’s ever-changing layout, countless portals, and flexible geography make it a perfect home base for a West Marches campaign.

DMs are encouraged to:

• Choose any setting they find fascinating
• Invent or borrow worlds freely
• Drop players into any genre, tone, or timeline
• Ignore distance and travel logistics entirely
• Create missions that stand alone or link into arcs

If you want to run:

• Spelljammer horror
• A time-loop village
• A crashed spaceship
• Mythic Greece
• A cyber-dystopia shard
• A prehistoric dragon empire
• A haunted demiplane frozen at midnight

Sigil can open a door to it.

Living in the Cage

Sigil’s name among locals is the Cage, a reminder that you can’t leave without the Lady’s permission. Fortunately, most people don’t want to. Not when every service, every creature, every flavor, and every artifact from the multiverse eventually passes through the city.

Porters, guides (touts), and sedan-chair bearers navigate its twisted streets. Markets churn with impossible goods. Taverns cater to the preferences of every species. Cranium rats scurry through alleys, and razorvine threatens anyone foolish enough to lean against the wrong wall.

Life here is messy, loud, diverse, strange, and absolutely alive.

What Sigil Means for Our Campaign

Sigil is the central hub of our West Marches game—a place where:

• Characters from any background, world, or timeline can appear
• DMs can take players anywhere they imagine
• Missions can explore any era, plane, or alternate history
• The stakes can go from street-level to cosmic in a single session

Sigil doesn’t limit our stories—it unleashes them.

It is the starting point for every adventure, and the destination you return to when the mission ends. A city held together by impossible physics, ruled by an impossible being, thriving on impossible diversity.

And through its doors, anything is possible.

If you’d like, I can generate matching posts for each ward of Sigil, articles on portals, faction primers, or a player-friendly guide to traveling safely in the Cage.