Monkey Forest Road

It's called that for a reason.

The hotels and trees are filled with long-tailed macaques, climbing, snacking, dodging taxis to cross the street. 

You can also pay to visit the Monkey Forest sanctuary. But they're famous for stealing hats and sunglasses and any snacks in your bag. More info: http://www.monkeyforestubud.com/

Hanuman, the Monkey King, is everywhere.