Early 1970s. Initially used mostly for mid-sized carnivores (hyenas) and a few smaller goat/antelopes (gorals etc). Seems like they modify them slightly every few years for changing purposes.
Besides Chinese gorals, other ungulates that lived in these grottos include Himalayan goral, Red goral, Saiga, Siberian bighorn sheep, Bharal, East caucasian tur, Japanese serow, Rocky mountain bighorn sheep, Desert bighorn sheep, Spanish ibex, Rocky mountain goat, Dalls sheep, and Masai klipspringer.
One macropod that is currently being kept in these grottos is the Yellow footed rock wallaby
While volunteering at the Los Angeles Zoo a while ago I overheard some people complain that the zoo keeps animals (specifically Markhors and Bighorns) in horrible concrete exhibits and that they will never return, and instead they will go to the "famous" SD Zoo because they would never keep animals in all concrete exhibits...
And that's not the first comparison I've heard between the two zoos that makes no sense at all!