In my day the park had a massively tall sing set that was thrilling to ride when pumping high enough to see over the bar into the adjacent monkey island.
See Places Together on one map.
Columbian Park and Zoo. 40.414531, -86.871481 Columbian Park
Friends founded the "friends of the zoo" which was more aligned with the animals than the zoo administration. It appears that decriped old cage buildings have been raised and the large animals found happier places to end their days.
I took my new girlfriend to the park to pass the time on a one summer evening on a bench swing just across Main street from a tavern with the self-proclaimed coldest beer in town. We've been zoo fans ever since.