The Bank Of Finland Museum is a hidden gem. There's a great, multilingual display of early and modern monetary systems, coins, banknotes, banknote art and historical objects. The display is classy. There's also a changing, seasonal exhibition. The museum is relatively small, you'll only need to sacrifice 30 - 60 minutes of your time. Guided tours for groups are available, if booked in advance. There's also a small gift shop and a cafe.

 Entrance is free,  Address is Snellmaninkatu 2, Helsinki. (The museum is located near the Senate Square.) Website: