Banks are found all over Arelith in most any reasonably civilized place. Banks are a good place to store your money in case you die. When withdrawing or depositing money you can specify an amount to transfer from the bank to your pocket, or vice versa, or you can simply type 'all' or nothing at all, as long as the last thing you said wasn't a number, to transfer all your gold.
Other Bank services include: transfer of gold to another character's account, managing faction bank accounts to which you have access, or take a loan of up to 1000 gold pieces, resulting in negative balance of -1000. This is specially useful for new characters.
Banks have a hard 10.000.000 (10 mil) GP capacity. If you want to store more, you can use the Factional bank.
Banks can be found in basically every settlement of the servers, such as Cordor, Brogendenstein, Andunor.
Different special locations also provide bank services, including certain quarters.