On 06/09 I spent the whole day in the American Museum of Natural History and I had to hurry to see every exhibition. It shows all kind of animals from all over the world as well as the evolution from the first life until the Dinosaurs. You can also watch a space show about the Big Bang and the Universe.
Further you can see human cultures from all over the world and the evolution of men (if you want to believe it). They also have a large collection of minerals and elements from the whole periodic system.