Mystical City Planning

Dis: Birthplace of the Double Down.

In fact, very few people on the face of the planet know that the very shape of the M25 forms the sigil odegra in the language of the Black Priesthood of Ancient Mu, and means "Hail the Great Beast, Devourer of Worlds."

— Good Omens

Sometimes the best way to conceal your hex, summoning circle, or glyph of protection is in plain sight using sheer scale. This is usually through some facet of a planned town or city, such as its walls, street layouts, sewers, and the like, but scale-wise, this can go from a single building to an entire country. The symbol usually passes unnoticed to all but a few or is completely forgotten, and is only discovered through either its blueprints or a bird's-eye view. Its appearance usually constitutes The Reveal.

It is a specific form of urban planning designed to invoke mystical power, usually Geometric Magic that's Hidden in Plain Sight, such as a sealing spell for Sealed Evil in a Can that's buried underground or a protection spell for the location. The more dangerous forms are a kind of Malevolent Architecture that wreak eldritch havoc when activated. Worth mentioning that this can overlap with Connect the Deaths, if there is a mystical meaning behind several murder locations that somehow incorporates existing elements of a city's design. The key to this trope is that the shape itself is a spell on a monumental level.

Compare Crop Circles for other shapes visible from the sky. This is usually designed by The Conspiracy.

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Examples:

Anime & Manga

• Fullmetal Alchemist does this with the entire country of Amestris, which was designed to be a giant transmutation circle for Father's plan.
• Kishin Douji Zenki: The entire town turns out to be in the pattern of a pentagram designed to keep the Big Bad from breaking free.
• In Magical Shopping Arcade Abenobashi, figurines on four historic buildings prevent gates to alternate dimensions from opening, and the destruction of the last of them leaves the neighbourhood unprotected. Or so you're initially led to believe. The figurines were only minor talismans — everything is happening because the main character can't cope with literal destruction of his childhood.
• X/1999 boasts CLAMP Academy, a school whose buildings and campus were designed and arranged to form a spell capable of sealing the Sacred Sword. There's also... y'know... the massive pentagram created by its monorail system.
• In A Certain Magical Index: Miracle of Endymion, it's revealed that the Endymion space elevator was actually built in order to be the center for a magical circle large enough to encompass the entire earth. The scale of the structure on its own was enough to give it magical significance, but everything about it was built to channel a specific spell. The core room's true purpose was to house the center of the spell, and allowed the villain, who otherwise couldn't wield magic, to direct the spell.
• In Slayers, Saillune's capital city is built with a series of defensive walls in the shape of a hexagram (Bowdlerised to a pentagram in the Slayers Revolution anime), which boosts the power of White Magic while weakening spells of other types.

Comic Books

• Downplayed in From Hell when Dr. Gull has Netley, the carriage driver he recruited to assist him with his murders, take him on a tour of London, stopping at various landmarks and locations and expounding on their mystical significance, noting that the modern world has forgotten these aspects. When it's all over, the not-very-bright Netley admits that pretty much all of what Gull talked about has gone over his head, but is horrified when Gull points out on a map that the locations they visited are laid out in a pentagram pattern.
• The Knowledge is the name of all the routes, roads and geographical information London cabdrivers need to know before they can get a license. In the Hellblazer spinoff Chas: The Knowledge, we're told it's actually a complicated sealing ritual to contain a demon.

Fan Works

• Twice in The Alarmaverse series.
  • In Alarm Clock, Ditzy discovers that Ponyville's Town Hall has the same floor plan as the ancient temple of an Eldritch Abomination. And that other ponies have accidentally completed the ritual to summon that monster.
  • In the sequel Beauty Will Tear Us Apart, Ditzy researches other buildings by the same architect, and finds that the Goggle Heights Art Museum has the same layout as a Hyperborean Echo Labyrinth, and is capable of creating monsters out of sound waves.

Films — Live-Action

• In Ghostbusters (1984), Ivo Shandor designed a building in New York for the sole purpose of channeling mystical energy, to open the gateway for Gozer to enter Earth. He then disguised this building as an apartment complex.
• Sherlock Holmes (2009) points this out during Sherlock's explanation of figuring out Blackwood's Connect the Deaths scheme: he says that cities have encoded references to the Masonic beliefs added to their design, which Blackwood has used to amplify his pretense of having come back from the dead. And using this, he discovers that the last target of Blackwood's "dark magic" rampage will be The Parliament.
• Iron Man 2 has a sci-fi equivalent. Howard Stark theorized a new element back in the 70s but was unable to actually synthesize it, so he designed the grounds of the 1974 Stark Expo as a blueprint of the element in hopes that his son Tony would eventually find and decipher it to create what he couldn't.

Literature

• Played for Laughs in Good Omens, where the M25 motorway forms a demonic sigil that translates to "Hail the Great Beast, Devourer of Worlds." Crowley considers it one of his finest demonic works as it generates all sorts of unpleasantness from its drivers. Becomes a Chekhov's Gun when, in a rush to save the world, Crowley must pass through said motorway, which results in his car bursting into flames.
• The People's Palace from the Sword of Truth series is the seat of power of an ancient ruling wizard dynasty. It is built in the shape of a giant spell meant to empower any wizard from that dynasty and drain the power of anyone who is not, and powered up by the blood of all the people walking through its corridors. However, it's not quite unnoticed — one visitor managed to navigate it easily simply by knowing the spell.
• This is The Reveal in Brandon Sanderson's Elantris. The eponymous city is a focus of magical power and its inhabitants are the next thing to physical gods. But just prior to the beginning of the book, the magic fails and the blessing becomes a curse. The protagonist eventually figures out that the magic system — and the design of the city itself — is based on a glyph which represents the basic shape of the continent, and a disaster caused a huge chasm that renders the shape inaccurate. Drawing a line to represent the chasm corrects this.
• In The Silver Chair, a message from Aslan is hidden in the ruins of a giant city. The words are part of a carving that was basically "Ozymandias", not part of the city itself. The letters are large enough to walk into because they were made on a giant's scale, and because of this size, the characters aren't immediately aware that they are letters.
• In The Stormlight Archive, ancient cities like Kholinar are built with complex radial symmetry that matches specific cymatic patterns. Since symmetry is sacred to the Vorin church, some in-universe scholars take this as proof that those cities were built with divine guidance.
• In the Illuminatus! Trilogy, it's implied that The Pentagon is built that way because of the occult significance of the shape, and that it's housing some sort of Eldritch Abomination.
• In the Rivers of London novel Broken Homes, Skygarden Tower is a tower block designed by the architect Erik Stromberg, who the Faceless Man suspects was a practitioner, and created the building to be a magical piston, storing energy from everyone who lived there, to be released by the building's destruction. Peter realises he was only half right; the glass "stadtkrone" at the top of the tower was intended to transmit the magic across the city when it reached a certain level, no destruction necessary. Smashing the stadtkrone prevents the Faceless Man from gaining the power, but not the building from being destroyed.

Live-Action TV

• In Bones during the Gormagon arc it is noticed that the Gormagon's kills are mapped in the form of a pentagram, which correspond with some significant structures in Washington, DC.
• Good Omens (2019): Mirroring the book, Crowley designed the M25 motorway as a massive demonic sigil that acts as a massive prayer wheel, producing just a little more evil whenever someone drives on it. We get to see the buildup a bit more (including the part where Crowley sneaks out and physically moves build markers a few meters to make it work), and his presentation on the project to his fellow demons.
  Crowley: Can I get a "yahoo"?
  Demons: [deadpan] Yahoo.
• One of the major season-ending twists of Supernatural involves a Reveal that a hundred-mile-wide system of train tracks in the US Midwest actually forms a huge protective seal over a dormant Hellgate. The Winchester brothers break the circle.

Tabletop Games

• Dungeons & Dragons supplement FR6 Dreams of the Red Wizards. The city of Eltabbar in Thay is built in the shape of a huge glyph to confine a demon prince called Eltab. Making maps of Eltabbar is forbidden, because if the city is accurately mapped and the map is then destroyed, it reduces the power of the restraining glyph. If this occurs enough times Eltab could be freed, which would be a disaster.
• In Exalted the city of Whitewall (originally Ondar Shambal) was designed as a city-sized Amplifier Artifact that would magnify all prayers to the Unconquered Sun.
• In Magic: The Gathering, the city of Ravnica was designed by Niv-Mizzet to form a giant sigil powered by the movement of its citizens that would give him ultimate power. However, a goblin tribe involved in the construction spotted what he was doing and sabotaged the design. When Niv-Mizzet found out what they'd done, he was so impressed with how they did it that he bought the entire clan and made them the basis for his guild.

Video Games

• Dragon Age II has the City of Kirkwall, revealed in the Enigma of Kirkwall to form one of these: "In the oldest parts of the city, one can make out the outlines of glyphs in the very streets! What manner of magic is this?"
• Emperor: Rise of the Middle Kingdom: Each building and terrain type is associated with one of the five elements; your city's feng shui score is set by the proportion of buildings that are built on elementally harmonious locations. A more harmonious feng shui score improves your approval rating, your city's health, and the efficacy of your Offerings to the Gods.
• The city of Ehn'Gha in Eternal Darkness has nine towers that form a giant spell circle. This is the only way that the player can cast nine-point spells, which are powerful enough to nearly destroy the entire city or summon Ancients.
• Final Fantasy XI introduced one of these with its Seekers of Adoulin expansion. The Rala Waterways, the underground aqueducts, form a geomantic glyph of protection for the city. They have been sabotaged so that the water flows the wrong way, so instead of banishing demons it is now summoning them.
• Ghostbusters: The Video Game has one in the buildings designed by Ivo Shandor, which form a Mandala on the map of New York.
• In The Legend of Zelda: Spirit Tracks, the entire rail network is a giant confining seal for a demon.
• The City from the Thief series is revealed in Deadly Shadows to be the Final Glyph that, when activated, drains all power from the rest of the glyphs that the Keeper magic is based upon.
• Magnasanti, a town built by Vincent Oscala using SimCity 3000, is shaped after the Bhavacakra—the wheel of life and death in Buddhism. Unsurprisingly, it is a totalitarian hellscape with over six million citizens, where nobody lives to retirement age the people spend their entire lives in a tiny block of space, with no access to education, healthcare and fire response.
• In Vagrant Story, the city of Leá Monde itself is actually the Gran Grimoire, the ultimate codex of magic. Incantations carved into the very stonework of the city made it into the source of The Dark. As a result, anyone who spends any length of time in the city will develop magical abilities...and lose their souls to the city in the process. Whoever has the literal key to the city, the Blood-Sin tattoo, holds power over its magic and the lost souls within it.

Visual Novels

• In the visual novel Chrono Clock, the fictional city in which the setting takes place in is built around a giant monument, which when viewed above, is deliberately designed to act like a sun dial. This was conceived by Rei's grandfather to worship the Goddess of Time; Chronos.

Web Videos

• In Dimension 20's second Season, The Unsleeping City, the highways of the city of New York are a glyph designed to dampen magic, created by Robert Moses.

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