I was just looking at the Smithsonian National Zoo, which has free admission but the most expensive parking fee I have seen. Since every zoo and aquarium and museum in my state of Arizona has free parking, this was quite a shock. I think all zoos should have free parking. My goal here is not to list EVERY zoo that has paid parking, but only those that are unusually expensive. For the sake of definition, I will say those that are at least ten dollars or ten euros (or equivalent in other currency).