This is the viewing as from the new windows at the lower viewing area. It looks dark because for some reason the windows are clouded as if they are old.
@Zooish no, the plants are free-ranging. Small plants have been put in all around the walls and around the climbing structures - I thought they'd have been pulled up within a few days of the chimps being let back in (especially because there are some younger animals in the troop) but apparently they aren't interested in doing so.