The Bank is a two-tile industry always located in Towns. The temperate banks never appear on a newly generated map, but spawn during the game (in any year) in towns with 1200 or more population. The sub-arctic and sub-tropical banks are available from the start, and appear in towns of any size.
The main difference besides appearance is that the temperate bank produces the resources it also can accept, while the sub-arctic/sub-tropic version only accepts materials.
Banks never close down; they stay on the map forever. Temperate banks never increase or decrease production of valuables (except for the change between 8 and 9 productions per month; see game mechanics).
Funding a bank
Funding a bank is possible when the appropriate advanced setting is enabled. You can only fund banks in a town. In the temperate climate, the population must be at least 1200. The cursor will indicate the upper right corner of the 2x1 squares that the bank will occupy. The complete footprint needs to be on top of house(s).