Neil Armstrong stepped onto the surface of the Moon on 20 July 1969.
As he did so, he spoke some very famous words: "That's one small step for (a) man, one giant leap for mankind."
The American astronaut was the first human on the Moon, and was followed by Buzz Aldrin. Aldrin described it as "magnificent desolation".
They spent 21 hours on the Moon, including a seven hour sleep, before lifting off back to Earth.
Since then, only 10 other men, and no women, have been to the Moon.