"Banking city" does not mean there's plenty of bank branches around :-) Companies in the same industry tend to gravitate around each other so they can cluster

"Banking city" does not mean there's plenty of bank branches around :-) Companies in the same industry tend to gravitate around each other so they can cluster talent, lobby governments and "build synergies" (sorry for the buzzword), among other reasons. The City of London is that kind of cluster.