When I was a kid, I went to day camp on the grounds of Cantigny.
Built by Colonel McCormick's, the powerhouse behind the Tribune, it has a fantastic WW 2 musuem, and beautiful grounds with tons of flower gardens and walking paths.
It also has a Golf Course and restaurent, where you can get a superb, pricey lunch.
It use to be free to get in, but now i there is a per car fee.
I don't know if they are still there, but there use to be a "playground' of tanks you could climb on.
A fun, educational adventure for families.