1. Montague House, the first British Museum before 1845 because they had three giant giraffes on the grand staircase and based on the watercolor by George Scharf it looks so cool.
The day the mastodons left
2. London Zoo in the late 1800's when they had pretty much everything including Jumbo the elephant and the one Javan Rhino they had in the 1870's.
3. King Louie 16th's menagerie at Versailles (before the French Revolution) because I saw his mounted Indian Rhino in the Musee National D'Histoire Naturelle and the gardens there are cool.
4. Vincennes Zoo, Paris when the mighty Siam was still alive (pre-September 1997). I got to see his mounted hide in the Musee National D'Histoire Naturelle though.
5. Bronx Zoo in the 1960's when the James' Flamingo was rediscovered in the and the zoo had a small colony in their flamingo exhibit.
6. Toronto Zoo before 2011 when their Gaur bull, Hercules was still alive.
7. Oregon Zoo to see the elephants Packy and Tusko before they passed away.
8. Any zoo or facility with a huge bull Southern Elephant Seal.
9. Whipsnade Zoo when you could ride their Indian Rhino "Mohgan".
RRC: Whipsnade 1953
10. Any zoo that had Chacma or Yellow Baboons.