The National Air and Space Museum of the Smithsonian Institution, also called the NASM, is a museum in Washington, D.C.. It holds the largest collection of historic aircraft and spacecraft in the world. It was established in 1946 as the National Air Museum and opened its main building near L'Enfant Plaza in 1976. In 2014, the museum saw approximately 6.7 million visitors, making it the fifth most visited museum in the world.