I don't think Helsinki existed back then: Tallinn was quite important though.

The key Hanseatic cities were the German coastal cities eg Lubeck, Hamburg, Danzig as was, although London and Bergen were both very important trading hubs which had "Kontors" - sort of trading enclaves: London's "Steelyard" was where Cannon Street station is now.

"Any economic unit can emit money. The serious problem is to get it accepted" Hyman Minsky