I'm lucky enough to have visited many great zoos, such as the ones in San Diego, Washington, DC; Memphis and the Bronx. The St. Louis Zoo is among the best in the country. Beautiful, huge grounds filled with the leaves changing colors and Halloween decorations. Fascinating both outdoor and indoor penguin exhibits. Hippos can be viewed underwater. Large variety of big cats, such as lions, jaguars, and cheetahs. Polar bears weren't visible today, but we saw grizzly bears.
Don't know how the St. Louis Zoo manages to be free, but it's fantastic. The first hour during our Sunday visit the paid attractions of the stingray pool, carousel and children's zoo could all be visited for free. Only charge was $15 to park.
Wow! What a great day!