I am not sure when we stopped building the city and it started to build us. Over time, we had forgotten how to tell our own bodies apart from its towers. Our skin was what gave flexibility to its composite materials. That was when the city withdrew pipes and struts from the regolith and began to walk.
Or were we the ones walking? I flew the ship sent out to investigate, to present itself to the now-alien face of our home, moving smoothly forward, leaving behind only the mines and quarries where all of us had been made. I saw nothing in the scanners of its eyes that gave away the city's intentions.
As we slid through new landscape, change became routine. We still worked. But our engineering projects became stranger. We hatched a sports arena beneath the bare, seamed rocks of a mountain summit, where the atmosphere was thin. The city settled there for weeks, while we watched lights coming alive over the stadium's vacant oval. Photons battled dust for the championship. There is nothing lonelier than an arena that will never know a crowd.
Like us, the city was thirsty for metals. We found an iron well and lowered parts of ourselves into it. I was extruded as an individual to keep watch, my mind converted to nothing but electricity shivering through a fragile network of water and fats, my skin stiff with feathers. I flew in spirals, observing, until we had drunk the iron down to nothing but shining froth.
We met other cities unhinging themselves from the dirt just as we had done. They lumbered along beside us, creating a herd of biometropolitan beasts.
Now we no longer moved in silence. Every frequency streamed with our communications. We talked about a time when cities wouldn't just build their inhabitants, but also the planet itself. Eventually, the city would absorb the world.
I am not sure when we stopped building the world and it started to build us. Pipes stretched into roots; leaves fed engines. Where did the mountains end and the cobblestone roads begin? Every material — synthesized, bred, or forged — is just a lattice of atoms, straining to fall apart. The city kept walking, but when we emerged from its shell, we could no longer see it. Or rather, we could not tell it apart from everything else on the planet.
All we knew was that the city grew or was grown, unfolding into landscapes better than anything nature could have invented on its own.
The art that inspired my flash fiction today is by award-winning Sony concept artist Cecil Kim, who has worked on several videogames and films. You can see more of his incredible work on his website.