Location of discovery: Mercury
Source coordinates: https://www.google.pl/maps/space/mercury/@84.4842326,84.6684841,120407m/data=!3m1!1e3
Here is an interesting structure in a crater on Mercury. According to the map ruler, the structure is 5 km wide and 10 km tall. The crater it sits in must be about 12km deep because the structure does not exit the crater ceiling area. Why oh why would aliens want to build a structure directly in the middle of a crater where it obviously stands out? With a species able to construct a 10km tall structure...its just absolute proof of intelligent beings out there. Even with less gravity on Mercury...still an incredible achievement.
Scott C. Waring