I'm posting this from a public terminal because I don't want this tied to my BCI. I found an entrance to a Lost Block. I went in. I came out. I am not going back.

I've been exploring the Underworld for three years — the service tunnels, the abandoned infrastructure, the spaces beneath the city that nobody maintains and nobody monitors. Most of it is exactly what you'd expect: dark, wet, full of rats and the occasional squatter. But in October I found a tunnel in the sub-basement of an abandoned water treatment facility near the Shelf that didn't match any map I had. It went down when it should have gone horizontal. The walls changed from concrete to something smoother — not metal, not stone, something in between. The air changed. It got warmer. It smelled different, like ozone and cut grass, which makes no sense underground.

The tunnel opened into a basement. The basement had stairs going up. I went up. I came out onto a street. A real street — paved, with buildings on both sides, streetlights (working), and sky above me. The sky was wrong. Not wrong like a different sky — wrong like a photograph of sky, like someone had taken a picture of a clear day and pasted it overhead. The light was even, shadowless, and it didn't change in the twenty minutes I was there.

The street was clean. Not clean like maintained — clean like unused. No litter, no scuff marks, no gum on the sidewalk. The buildings were intact, maintained, with doors and windows. The windows had curtains. Some of the curtains were drawn. I walked for twenty minutes. I saw no one. I heard nothing except my own footsteps and a faint hum, like electrical infrastructure running at capacity. But I felt observed. Not watched — observed, the way a specimen feels observed. Something was aware of me. Something was taking note.

I turned around. The basement stairs I'd come up were gone. In their place was a different stairway leading down to a different tunnel — same smooth walls, same warm air, but oriented differently. I followed it because I had no other option. I walked for maybe ten minutes. I came up through a service hatch into an alley three blocks from where I'd gone down, on the surface, in the normal city. My BCI showed no gap in my location data — according to my navigation log, I'd walked a straight line through solid buildings.

I've been back to the water treatment facility twice. The tunnel isn't there anymore. The sub-basement ends in a wall. I am not going back.