Of course it is a topic of much discussion and mystery, how these colossal stone heads were moved without the use of modern technology, but as with all topics I post about, I do not claim to know the answers. I just love to read about it from as many sources as possible. Here are a few links that lead to different theories about how the statues were moved. Some people think aliens used their advanced technology to create these stone giants to resemble themselves, others think the statues could have been walked to their location with much less effort than would be expected. Believe what you will.
Discovery is always a website to go to if you want the facts. At least that's my humble opinion, but I'm by no means a scientist or archeologist, so it is not my decision to make on what the "truth" is.
Livescience.com is also a very reliable source if you want to know about anything involving science. I tend to take this source as very reliable.
This article displays visuals on how the statues may have been walked to their location and goes into quite a bit of detail on the matter.
I don't know how credible this site is, and there is always the possibility that this picture was photoshopped, but if the picture is real, it makes you wonder if it is possible to simply walk this statue from one place to another, especially over a distance, even with a small army of individuals. I for one love the mystery of not knowing.