The Neil Armstrong Operations and Checkout Building (O&C) is a historic building on Merritt Island, Florida, United States. The five-story structure is in the Industrial Area of NASA's Kennedy Space Center. Its has twin-block facilities that include the crew quarter dormitories for astronauts, suit-up preparations prior to their flights, and the other is a large spacecraft workshop used for manufacturing and checking activities on crewed spacecraft. On January 21, 2000, it was added to the U.S. National Register of Historic Places.

Apollo 11 was the American spaceflight that first landed humans on the Moon. Commander Neil Armstrong and Lunar Module Pilot Buzz Aldrin landed the Apollo Lunar Module Eagle on July 20, 1969, at 20:17 UTC, and Armstrong became the first person to step onto the Moon's surface six hours and 39 minutes later, on July 21 at 02:56 UTC. Aldrin joined him 19 minutes later, and they spent about two and a quarter hours together exploring the site they had named Tranquility Base upon landing. Armstrong and Aldrin collected 47.5 pounds (21.5 kg) of lunar material to bring back to Earth as pilot Michael Collins flew the Command Module Columbia in lunar orbit, and were on the Moon's surface for 21 hours, 36 minutes before lifting off to rejoin Columbia.