In regard to Puma Punku- there's a lot more conventional explanations for many of the things that are there, than you may be aware of. Extra-terrestrial assistance seems to be the easy knee-jerk answers for many unexplained things, and Puma Punku at first glance is no exception.
But when you take a closer look- the ruins are diorite and andesite, scarcely impenetrable (as Granite would be). Copper tools have been shown to have made groove in the stones found at Puma Punku. In fact, one reason for the E.T. claims have been the famous 1 cm grooves running down the stones and of which have been claimed to be very precise. This has been found to not be the case- also there are stones with unfinished grooves that bear marks of copper tools.
And while the carvings, fitting, and transportation of large stone seem to defy explanation- we keep forgetting that people back then essentially had the same brains we do now, and while their technological astuteness is not as refined as it is now, they still had a great deal of intelligence, and mastering stone was an art and a science to them.
For example, carving a stone wheel would be considered "very easy" today, but if you look at it practically, who would even know how to do that, much less have the tools to do it? It is something we know is very easy to do, yet we have no skill to do it because we no longer need to do it, so to speak. In that vein, it is easy to assume that people were "dumb" back then, and the presence of those extraordinary stones were therefore the result of extra-terrestrial interference.