Buildings are constantly sliding, turning, merging, separating. Directions: "Your destination will arrive in 1.5 hours."
They covered the city with meadows of grass, then after a year, built roads where foot traffic had worn grass to dirt.
You can't throw a stone without hitting a beautiful park, playground, museum, or library to which admission is always free. But this edifice is funded by the anguish of one child, trapped in an underground movie theater at the heart of the city.
All doorframes and archways and staircases with people of ambiguous gender lounging in them.
With each infinitesimal tick of time, the city inches infinitesimally forward in space, shrugging off its past like a snake sloughing off its skin. Upon the Great Plain, you may view the marvelous and continuous brick of its past (for a modest viewing fee).
The city is a living monument to itself. Every object bears a plaque noting its name, date of creation, origin, and provenance, with some flavor text. Every resident secretly hopes that the Curator will feature them in an exhibition while they're still alive. Past exhibitions include "CITY MUSEUM: A STRANGE NEW BEAUTY" and "CITY MUSEUM: A RETRO-SPECTIVE."
Directions are given recursively. "Go to the middle triangle, then to its top triangle. Repeat until you arrive." Directions might not terminate.
Built by a crazed Borges fan, this literary theme park features life-size replicas of the Library of Babel, the Garden of Forking Paths, and Babylon. At least, that's what this travel guide tells us. But wait, another copy of the same travel guide doesn't have an entry for this city—
Creating symmetry is considered an abomination unto God. The residents used to put considerable effort into constructing asymmetric objects: spiked buildings, diagonal clothing, beakered vessels. But since they started outsourcing manufacturing to SYMMETRY CITY (which had much better economies of scale), residents here just stick googly eyes on the symmetrical object in question.
Speed up the clock tower and everything runs faster. Drop a magnet and the city grinds to a halt—at least until the repairperson arrives.
Every time you reach an intersection, you take all of them at once. There are few maps of the city, because you'll always find what you're looking for.
Every point in the city is immediately adjacent to every other point in the city. There are no maps of the city, both because no one needs one, and no one can draw one.
We don't even have to visit to know that this is almost certainly a horrible dystopia.
The city is a mess of sewer pipes, subway tunnels, telecom fiber, manholes, utilities pipes, power lines, railroad tracks, cell towers, and submarine cable landing sites. They cross-breed into complex and powerful structures of unknown purpose. Great destination for nerds.
People have grown on perpetual lattices and outlines like grapevines on a trellis. Directions: "Go to where the main street ends abruptly, enter the shantytown, take a left at the unfinished clock tower, and meet me at the makeshift church."
It's always night. The streets are entirely silent. Every window is lighted.
The one virtue of this city is that all construction must be done by songbirds. Thus, people here love waking up to construction noise. Among all the Invisible Cities, ONE VIRTUE CITY is the most populous.
Guess how they designed the grid?
There are no plazas, Main Streets, or thoroughfares. Due to space constraints, the city is a one-mile-by-one-mile ten-storey heap of narrow alleyways, wooden tenements, and fire escapes from those wooden tenements. Like a rainforest, the most powerful live closest to the light in the canopy, and the poorest live in the dark sediment on the floor, scavenging for dropped objects and for light.
When you arrive, you are disassembled into tendencies that are then absorbed by the appropriate probability distributions. You made it a little more likely that a certain apartment would be occupied; you made it a little less likely that a certain bus would arrive on time. You made the city a little more likely to exist.