To anyone who harbors the dream of becoming an astronaut or pilot, the Udvar-Hazy Center in Chantilly, Virginia is heaven on earth.

The 760,000 square-foot facility—a companion site to the Smithsonian National Air and Space Museum on the National Mall—is packed to the gills with aircraft and spacecraft. It celebrates its 15th anniversary on Saturday with a day of presentations, concerts, and film screenings.

The free event runs from 10 a.m. to 3 p.m., and parking will be free throughout. View the full schedule of events here.

The museum has hosted nearly 20 million visitors since it opened on a freezing winter day in 2003. It was an instant hit: In its first two weeks, more than 200,000 people visited.

The center is made up of two hangars, one focused on air and the other on space. The Boeing Aviation Hangar houses around 170 aircraft, including the Enola Gay, which dropped the atomic bomb on Hiroshima during World War II, and the Langley Aerodrome, a pre-Wright Brothers airplane from 1903.

The crowning jewel of the James S. McDonnell Space Hangar is the space shuttle Discovery. If you lived in D.C. in 2012, you might remember the April day when it was flown over the city and everyone lost their minds. Visitors can also check out dozens of rockets, space capsules, satellites, and other artifacts.

And if you ever wondered where the Center gets its rather unique name, here’s the answer: It’s named for Steven F. Udvar-Házy, the former CEO of Air Lease Corporation. Udvar-Házy was born in Hungary and moved to the United States with his family when he was a boy. He become a billionaire in adulthood after founding a successful aircraft leasing business. He donated $65 million dollars to the Smithsonian Institution for the center.

This story was originally published on WAMU.