The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. 

It has free admission and is open 364 days a year. In 2016, with 7.1 million visitors, it was the eleventh most visited museum in the world and the most visited natural history museum in the world. 

Opened in 1910, the museum on the National Mall was one of the first Smithsonian buildings constructed exclusively to hold the national collections and research facilities.  The main building has an overall area of 1.5 million square feet (140,000 m2) with 325,000 square feet (30,200 m2) of exhibition and public space and houses over 1,000 employees.

The museum's collections contain over 145 million specimens of plants, animals, fossils, minerals, rocks, meteorites, human remains, and human cultural artifacts, the largest natural history collection in the world.

It is also home to about 185 professional natural history scientists—the largest group of scientists dedicated to the study of natural and cultural history in the world.

According to en.wikipedia