Surveyor 3

It has been fifty years since this lunar lander was sent to the moon. Launched on April 17, 1967, Surveyor 3 landed on April 20, 1967. Two and a half years later the crew of Apollo 12 visited Surveyor 3. They photographed the spacecraft and removed some of its instruments to bring back to Earth to study how instruments were affected by their time on the moon. This is the only space craft that we have launched that has been later visited by man.

You can read more about Surveyor 3 here.