When I was a little kid I used to like to go to the Central Park (NYC) Zoo and visit the monkey house since they were always active and acting up and thus great entertainment. My mother took me there quite frequently although she didn't much like the smell. In 2006 I visited there again and saw some of them outside hopping about on these rocks; I don't recall if there still was a monkey house, but I'd imagine so.
But here are the real things. Many of them hung around in trees.
Then there was this fabulous blue-balled vervet monkey as well as lots of baboons who were frequently seen hanging around in trees dropping fruit onto the ground. Sadly I never did get a good picture of a baby baboon riding its mothers back.