Birmingham might not have custom-built boulders in the centre, but I've been having fun on the concrete sculpture under the Hockley Viaduct during Lockdown 2. Some holds are chalked up .... own up, who else has been there? Am I in danger of cross-contamination!!??
First time I felt a bit self-conscious, but not many folk use these underpasses. Advantages of this wall: you can climb on concrete when it's wet, Birmingham Council allow climbing here, and it's close to home. Traversing is straight-forward, but you can find your own harder problems.
There (probably) is lots of good sandstone hard bouldering around where I live but you would really be trespassing (??) as the walls all belong to private tenements and I'm sure you (I) would not be welcome. As I live in the area I've not tried!
I've often looked longingly at the sandstone walls of the burgh hall in Maxwell Park...