The National Zoo is a free attraction, which is always a plus. The Zoo itself is very well laid out and very beautiful! However, don't expect many animals to be on display. Basically we saw no pandas, gorillas, tigers, even butterflies. None. Like some posters have said, they only saw prairie dogs which is basically true. Maybe it was just a bad day (it was pretty hot!), but do expect many empty displays. It was packed with people but didn't feel as crowded since the Zoo is quite big. Just don't get your hopes up just cause its free and is named "National Zoo"