Smithsonian National Museum of Natural History, Washington DC

Easily one of the best natural history museums in the US, and the entry is free! Has plenty of historic skeletons from prehistoric humans to extinct mammals and dinosaurs, as well as real mummies from ancient Egypt. I also recommend checking out the butterfly pavilion experience and other temporary exhibitions. A day's worth of interesting things to explore and learn about. They are also very transparent about which parts of an exhibit are fake replicas and which ones are originals, a small but important detail.

This Museum is amazing. It's like going back in time and looking at how everything came to be. The first floor us practically a cruise through the different time periods. The second floor has great things as well. I saw things that I didn't even know existed. Everything is so beautiful. I would go again every time I get the chance to do so because it's so much, you'll need a few visits to just take it all in and enjoy it.