Is it free? And I can't find there hours .

You can call 314-562-8430 for further information

http://riversidewildlifecenter.com/prices

I work there and it's not free. It's 10 for adults 5 for kids 7-12 and kids 4 and under are free. Most of the time we open up around 9:30-10 and we close at 5