Earth's Moon
There was evidence of colonization present on Earth's moon. This evidence has since disappeared. The race responsible for these colonies is unknown to us, our knowledge is not infinite.
The structures were characterized by stark geometric patterns. It is unclear how many beings would have lived on the moon colony.
At the time of this visit, there was an atmosphere on the moon but the planet Earth was not visible. The remains of a landing vehicle was found on the bleak moonscape.