Not much information is given on the Silver City. However, Lucifer passively mentions it in "Favorite Son", claiming that if Erwin Scoville (a security guard that was murdered) was not in Hell, he would be in the Silver City "enduring Uriel's welcome speech", something Lucifer deems "far worse than Hell."
In the show, Lucifer claims that the Silver City is the alternative afterlife to Hell, implying that the city is located in Heaven. In the comics however, a point is made that the city is only home to the Host of Heaven, and that the city actually exists "outside the created order of things".
Since Uriel, who was responsible for welcoming new souls to Silver City, is dead, it is unclear who does that now.
Eve implies she also did so for some time learn about how Earth had changed.