remembered visiting a building in Hong Kong where all the shops were just selling coins and banknotes, quite insane, don't think there are any other places like that in other countries
I don't think I've heard of any other places where the shops are all
numismatics-focused, but (the western sector of) the Hobby City mall in Moscow is about 50% coin/banknote shops, with much of the rest focused on other collectibles.
Reportedly there's a street in Paris that's all coin shops. Never been there so can't confirm.