Amalgam Station is found somewhere near the kuiper belt of the Cuidgari primary stellar system. Nobody knows precisely how old it is or who put it there. As far as Galactic history is concerned, it just happened.
C.M. Weller has published a WIP concept art of the station in hir blog. As you can see, it sort of resembles a Lionfish.
Amalgam Station has a mass roughly equivalent to a Dwarf Planet, but is much, much larger because Dwarf Planets aren't hollow or contain accommodations for millions.
It is a true melting pot of culture and understanding. At least, it is if you believe the tourist brochure. It wasn't that long ago that Cuidgari were actually fighting a land war in the extensive access shafts of Amalgam in order to win ownership of a very lucrative trade depot.
The primary unit of exchange is Time, and makes perfect sense as a unit of trade. Artists and workers alike are paid by the Hours, Minutes and Seconds they put into their job. Food is evaluated based on caloric need first and taste or texture a close second.
This has lead to the rise of artificial food. Naturally-grown or harvested foodstuffs are both too expensive and too nutritionally unreliable to sell in the Galactic Markets. Thusly, it is prized by the wealthy and exported from more agrarian planets by fast courier.
Employment and assistance in Galactic Society is assisted by colour-coded clothing, which means that citizens can tell at a glance what another citizen's knowledge base is.
There's always trade in illegal things, some of which are hazardous to life as we know it. This includes Unrestrained Cheeses.