Mentioned by washington.org
12 Can’t-Miss Free Museums on the National Mall | Washington DC
"The most visited natural history museum in the world, the National Museum of Natural History boasts an incredible rotating collection of 127 million items including dinosaur bones, the Hope Diamond, ancient Egyptian mummies and so much more. Prepare to be amazed, engaged, dazzled and more when you experience the museum's 31,000-square-foot Deep Time exhibit, where you can journey back millions of years and see dinosaur fossils, learn about past mass extinctions and their resounding effects and witness the evolution of life from the oceans to ashore. The museum reopens on June 18, so make sure to check its website for info regarding timed passes, health precautions and more."