Visiting the Iron Bank of Braavos is a special option in Braavos in MaB: W ACOK
You can buy cultivated or uncultivated land in Braavos. It will increase the prosperity of a town and produce money every two weeks that has to be picked up in the town.
You can also borrow money, however, you'll have to pay it back by the deadline at a 20% interest rate. If you don't have the money past the deadline then the interest rate will be increased to 40%.