How Do Historians Believe The Egyptian Pyramids Were Built?

There are all sorts of online resources to explain this. The best-illustrated one I've found so far is touregypt.net. It's also worth going to the National Geographic website and keying in "pyramids" - they have a really interesting explanation of how it was done.

By thousands of slaves using simple ropes and pulleys.( Actually it was the aliens!)

The cut or hued blocks of live stone, miles away south of the pyramid sites. They were shipped by barges north on the Nile River. Some people believe the workforce of small groups of off season neighboring farmers would pledge to perform the construction as a gift to their religion. Now here is where two different methods of placing the building were presented. One by use of simple levers and stacking of wood bundling under the slight move upward of each lift. The other was that a soil ramp was put in place temporarily to each level that the stone blocks were on rollers into placed.  There was one definitely peculiar theory that each block was poured as a concrete-like form inplace. Go to checkout all this head start help being provided to you.

They used sundried brick that weighed as much as a ton and stacked them on top of each other.