Though it is located in a suburb of Chicago, Brookfield Zoo is the largest zoo in Chicagoland.

Brookfield Zoo opened in 1934. The zoo currently sits on 200 acres and has more than 400 species of animals. The zoo is known as being the first zoo in America to recieve giant pandas. Brookfield is an excellent way to spend a day in the Chicagoland area. The park is beautifully decorated with lots of foliage. Though the park is not free of admission like the Lincoln Park Zoo, Brookfield is worth the fee to see all that it has to offer to a visitor.

Information from Wikipedia.