They've been there from what I assume, since the buildings opening. There's also three more exhibits like it.
Oh, then the building must need renovation, having opened in 1992. It's not good to put active monkeys in a tiny square exhibit.
I don't know, but it seems to have daylight through it. It could be a vast enclosure or another matching or smaller enclosure on the other side, but it's definitely something. In addition, you can't actually see the left-hand edge at the top of the enclosure either, so it could continue for fifty feet off to the left for all you and I know. Or it could extend or open out over the visitor pathway. Just worth bearing in mind when you look at one image of an enclosure that you are just looking at one image, and one angle. EDIT: Also - no food or drinking water visible. So there must as least be somewhere with a supply of water.
Not exactly, this is pretty much it without the remaining two extra feet that makes up the hidden door that can't be seen in the photo. The enclosure lighting is artificial other than the natural light that barely shines into the front of the exhibit. All four of the small Monkey exhibits at the start of the attraction are nearly identical.