At my last visit this part of the Monkey House was dank and dark and suffering from a misguided attempt to make it into a naturalistic rainforest, with free-roaming marmosets. Very sensibly, since the orangs moved out the hosue has been refurbished in Imperial style - much more sympathetic to the original design and a light and pleasant place to be now. The upper level features an exhibition about monkeys and apes in human culture.
The enclosures in this half are for mixed marmosets and agoutis, Red Ruffed Lemurs and Common Squirrel Monkeys - all have outdoor exhibits as well.