Moonsurface Crater

From the Introduction:

To the untrained eye the moon's surface might look featureless and dreadfully monotonous. And it is true, that this crater is only one among many. Not even the smaller crater in its interior serves as a real distinguishing landmark. Part of the craters wall has started crumbling, which hints at a higher age. Rocks are strewn around the craters circumference and at one spot its wall has even collapsed into a crude ramp of a sort. Only if one looks closely it will become apparent that this collapse was by no means natural. The rocks making up the ramp still show the hard edges of recent mechanical processing.