Between 400 to 700 years ago aliens visited the southwest of what is now the United States and the Native Americans and Spanish explorers that lived at that time documented their visit by carving petroglyphs on lava rocks.
This might not be the story you are given when you visit Petroglyphs National Monument but I think that the pictures speak for themselves. Here are my opinions on what we are seeing. I am not an expert but I think you will find my interpretations hard to dispute.
Look at the variety of spaceships here with the daunting grey alien on the bottom right. Fascinating.
Here is a space battle occurring in the skies above New Mexico. It looks like the bird shaped alien ship is on a collision course with the imperial frigate.
This next one seems innocent enough. You might point out that these are just hands. Well then why are there 6 fingers on some of the hands? The only answer can be aliens.
At first glance you might see just birds, but if you look at the figure at the bottom you will see the famous 1980 alien Predator. Coincidence? I think not.
This last one shows the wormhole that all of the alien ships appeared out of. I only hope that the wormhole has been closed.