Monkey City is the 4th upgrade of Path 3 for the Monkey Village in BTD6. It gives a free 0/0/0 Dart Monkey every round after you bought this upgrade. This bonus is stackable with other Monkey Cities. It also gives the Monkey Village slightly more range. It costs $2,550 on Easy, $3,000 on Medium, $3,240 on Hard, and $3,600 on Impoppable.