QUOTE(arthurlwf @ Sep 7 2012, 10:48 AM)
You based on an assumption that Egyptian definitely build it because it's located at Egypt.
Is it true? Nobody knows as it's full of mystery.
At the moment, there is no successful attempt to build a pyramid using current technological.Also, Pumapunku site is the most interesting because scientist has confirm that the stone cutting is similar to diamond cutting. Many people speculate that ancient peoples uses stone but that method would not shape a nice cutting stone.
Bottom line, we can only guess all the ancient mega structures is build with alien technology.
If use metal, the metal will rot through time
If use plastic, the plastic is not strong enough to build structures
If use organics, the substance can't withstand strong weathers
however using stone, it can last a very very long time
The question that we are asking about ancient civilization is similar to us asking "Can monkey build a a simple wooden house?"

Because there is no need for one? Currently there are much simpler ways to construct large monuments. Why follow the hard way?
There are many pyramids around the world(in different countries) and each of them are years apart. This shows that pyramid building is not unique to the Egyptians. Also, if the aliens did descent to show how pyramids were build, then these different pyramids from different part of the world would have been of around the same time but this is not the case when the carbon dating for all of the pyramids in the world are many years apart.
Pumapunku does not prove anything of what you said about aliens. Like I explained earlier, the technique is lost to us. It does not explicitly shows there is alien interference. At the moment, I can only see whatever you think that seems impossible to build is of alien tech. Didn't you consider that it is only the technology or the skills that were just lost to us?