Submerge some Relics of the Fifth City
From Fallen London Wiki
| Spoiler warning! This page contains details about Fallen London Actions. |
From: A Trading Post at Zenith: False Lights and False-Stars
The differences between their London and the one below may not be so great.
Unlocked with 
10 x Relic of the Fifth City, 
A Trading Post at Zenith 3
Success
A new familiarity
Is it the light that makes them look different, when you fish them out[…]? […] You brush a scattering of dirt off a street sign; you can almost remember the route there, starting from your lodgings. Only, of course, you can never have been that way.
[Find the rest of the story at https://www.fallenlondon.com]
You've lost 10 x Relic of the Fifth City
You've gained 25 x Nightsoil of the Bazaar
You've gained 6 x London Street Sign
