I'm not sure when it opened (1950's?) but I believe it closed around mid 90's. Before 1978 it held gorillas, orangutans, and gibbons. 1978 was the year that the zoo opened in open-aired gorilla exhibit. Now it is the 4D theater. Here's a photo of it.
http://www.cincinnativiews.net/images/Ape%20House%20Zoo.jpg