I think they pyramids are interesting but not unexplained. There is evidence of pulley mechanisms, and other methods has to how they were built. They haven't pinpointed it, but there are more than several ways in which physics could explain it. The ancient Egyptian's math skills were more than good enough to get the physics of pyramid building,  leaving this well in the normal not paranormal range.

Interesting... A triangular heap of bricks. Must've been them Aliens...

Is it all connected somehow? Did the aliens teach us to build them? Um... no. Its the easiest shape to build with the technology available at the time...

There is nothing that unexplained here. When you pile up a batch of cut blocks, the most stable edifice is a pyramid. The easiest way to get said blocks to said top of a pyramid is an inclined plane.  If you have lots of time, unlimited labor, and unlimited budgets, any mope can build a pyramid.

Certainly intriguing, and the construction techniques used are impressive, but its folly to make much of the similarities of the structures on either side of the Atlantic.  Given the materials and engineering abilities of the respective period, a pyramid-like structure is virtually the only thing that can be built that size.

These fly by night gimmicks won't last another 5,000 years but with the tenacity of our resident conspiracy theorist, the 600 helpfuls just might.

There are many theories of how and why the pyramids were built. Yet, no one can provide documented proof even of where the idea came from. Likewise, the similarities of the structures spanning the Atlantic Ocean when the Americas were still unknown. Interesting mystery.