Open 365 days a year and free! WHAT?! Yes, you read that correctly. The @lincolnparkzoo is open 365 days a year and is absolutely free. It is one of a few free admission zoos in the United States! The #zoo is 35-acres and was founded in 1868 (!) making it among the oldest of zoos in North America. Fun for all ages, this is one place you don't want to skip in #chicago.