Database: Banks (Assassin's Creed II)

REBECCA84: It looks like the Templars are using the banking network to transport their money. I bet you could snag some of that cash.

With the advent of double-entry bookkeeping, which allowed bankers to keep track of their clients' deposits and withdrawals, and the proliferation of many different types of Italian currency into the pool of circulation, banks became an essential part of everyday Renaissance life.

Banks technically couldn't make money on their money, because the Catholic Church forbade the charging of interest, but in practice this restriction wasn't followed by bankers, or even by the Vatican, which participated in the banking system and required banks to pay the Pope "gifts" in proportion to the amount of money he had deposited with them. As long as it isn't called "interest", God won't notice, right?