Location: 19°58'47.06"N 21°11'35.53"E
Going over Google moon I came across this strange structure on the surface. I searched the net and others have also found the same structure. Look at its hard right angles and massive size. It looks to be an alien base and not an ancient one. This one has no moon dust settled on it like most alien artifacts not he moon have. This one looks more recently built. To find the structure, just copy and past the location coordinates above into the google moon search. I am sure NASA has known about this base for decades...the only thing I don't know is if they sent a search and recovery mission to get alien tech or to see if the base is habitable. There also exists the possibility that there could be US marines stationed on there at this very moment...from what UK hacker Gary Mckinnon says he read about off world missions on high security US computers.
Above is side view, below is tilted view of same structure.