Once you meet Riebeck on Outer Wilds’s Brittle Hollow — he’s near the Crossroads — he’ll point you to the Hanging City.
The Hanging City has four districts, but you can only reach three of them. Below, we’ll walk you through each, and point out what you’ll learn there.
Hanging City — Meltwater District (2nd floor)
We’re starting with the third floor because it’s the easiest to get to — by falling through the black hole, and using the White Hole Station to reach the Northern Glacier.
From the Northern Glacier tunnel, head down. Follow the path and the stairs down until you find an elevator. Turn it on going down, and step inside.
At the bottom, follow the stairs down and onto the snowy path along the wall. Turn left and make your way to the ruins.
In the first room of the ruins, check the script on the wall to your left. Take the stairs down.
At the bottom of the stairs, grab the Nomai scroll. Head outside, down the stairs, and through the last room.
Read the second wall to learn of the Ash Twin Project (but you won’t get anything beyond the name).
Turn left. Down the first set of stairs you come to are the controls for the Black Hole Forge. Switch it to down so the forge raises to the top — that’s all you can do for now. (Just remember that this switch is here. We won’t be able to get into the Black Hole Forge for a while yet.)
Continue the way you were going to find the Hanging City’s central shaft and a directory of the districts. You can tell from the sign in the shaft that you’re in the Meltwater District.
If you walk between the two vertical shafts, there’s a long bridge — some of which will get destroyed as the planet collapses, so be careful — that leads back to the Crossroads and Riebeck.
Hanging City — School District (1st floor)
Either way you approach the School District — either from the Old Settlement gravity crystal path or by entering the Hanging City through the Crossroads and taking the central shaft down — you’ll start in the same room.
Most of your paths are blocked by ghost matter, so follow the only one you can until you reach an elevator beam. Take it up and keep following the path until you come to the schoolroom.
Read the scroll in the wall to learn about Nomai festivals, and then grab the scroll from the shelves in the back of the room. Swap out the scrolls and read about the Ash Twin Tower.
Head back to the entrance to the School District. On your left — facing away from the school toward the central shaft — there’s a building to jump to. Use the holes in the floor and the elevator to avoid the ghost matter. Take the elevator down to find one more scroll, and then use the elevator to return to the walkway. Pop this one in the wall in the schoolroom to read about the origin of the universe.
Hanging City — Eye Shrine District (3rd floor)
Use the central shaft to climb up to the 3rd floor. Follow the path left.
Jetpack your way up through the building and across any gaps. You’re heading for that large, shrine-like structure at the back.
Jump and jetpack down to the shrine (and the oxygen-replenishing trees there). Read all the script nearby — there are four panels of it.
Exit out the left side of the shrine, opposite of where you came in. Climb up through the ruins on that side, and watch for one more Nomai note on the wall.
Eventually, you’ll make your way back to where you started.
What have we learned? // What’s next?
The most tantalizing thing we’ve learned about the Hanging City is that the Black Hole Forge exists, but we can’t reach it yet — the central shaft is broken at the top. However, if you look at the symbol for the top floor on the Hanging City directory, it sure looks a lot like the teleporter (between the White Hole Station and the Northern Glacier). That will probably mean something later.
Beyond that, we’ve learned a lot about the Nomai, their culture, and why they were in this solar system — they were following the signal from the Eye of the Universe (which is older than the universe). We also know that their Vessel and one escape pod crashed into the Dark Bramble.
We’ve gotten several rumors about things to investigate on the Hourglass Twins — especially the Ember Twin. We need to look for Escape Pod 2, a quantum shard, the Fossil Fish Cave (and the anglerfish fossil inside), and the High Energy Lab there.
But before any of that, it’s finally time to investigate the Southern Observatory.