You are right, as with grass and plenty of climbing opportunities the 2 primate exhibits (one at either end of the central house) are definitely far from awful. I would like to see smaller primates in the enclosures as spider monkeys and siamangs both seemed on the larger size in comparison to the width of their exhibits.
@Onychorhynchus coronatus Yes, it was built in 1911 as there is a plaque or sign somewhere near the exhibit. The zoo opened a year later (1912) and this primate cage is probably the oldest structure left on the zoo's grounds. Does anyone know of anything else surviving from that era?
@snowleopard I think it is quite impressive / progressive in some ways for the time / era it was built but I dont think it is great nowadays (it isn't terrible either and would be much better suited for some other animal other than a primate).