If you want to see this building in more detail, then check out this funny stop motion animation review I made of it:
The building imitates the iconic Western architecture and has a unique shape, so as to make it more original when placed in a LEGO city. It is made up of three floors, the first of which ( the third one ) being designated for meetings of the bank's staff regarding financial performance and other details related to the bank.
The second floor is where the safe is, containing various precious stones, other jewels, coins and money. The safe is guarded by dilligent security guards. However, crooks also like to pay visits to this place.
The final floor, or the first floor ( or you could even say the ground floor ) is where the public has access, just like in a usual bank.