yeah but if aliens were here over 2000 years ago where are they now? and why would they have built them? space is so large that i don't think any life forms on any planets have ever met unless there planets are next to each other. I think you underestimate the human race as far as the pyramids there have been some very smart people in the past. Here is a thought for you Gizmo maybe we are the aliens? It is very possible.