I don't think that aliens haven visited Earth yet.As far as I know,if man wants to travel between galaxies,he must travel at a fast speed,especially near to the velocity of light .And the space outside is so large.So I don't think that aliens haven visited Earth yet.
I will show my friendly to him.And I will take him to my home as a guest.Tell him something about our Earth human beings instead of showing him around .Because I think if I take him around ,there must be a traffic jam all over the Earth!