How were pyramids built?

At that time (around 3000 bc) how were they able to put stone blocks one on the another? Did aliens help them?

In Ancient Egypt, there were no tools to build with or trucks to move things with. The Egyptians had to use their hands to make big blocks out of different kinds of sand, clay, and stone. After they made the blocks, they pulled them up big ramps onto the pyramid

Building a pyramid was difficult and dangerous. It required a highly organized society. Thousands of skilled and unskilled workers were needed. To complete the Great Pyramid at Giza, one huge stone block must have been quarried, shaped, and smoothed every two minutes for 23 years!
Building plans showing how the pyramids were built have never been found. However,experts use present knowledge about construction to make some intelligent guesses. Follow the four steps to see how ingenious_and hard working_the ancient Eqyptians must have been.

1) The enormous limestone blocks were taken off the boats near the pyramid site. If one block accidentally fell, it could crush to death hundreds of people.
2) Once uploaded, the limestone blocks were hauled on sledges over wooden rollers by gangs of men. Water or milk was poured around the sledges to help them slide.
3) Ramps, built of mud brick, were used to haul the heavy stones to the level where building was going on. To raise the stones higher, spiraling ramps were probably put against the pyramid sides.
4)A causeway connected each pyramid to the Nile. Built as a highway for the sledges, it eventually served as a corridor for the funeral procession.

Today's tools are made of steel. The ancient Egyptians used tools of copper, a softer metal than steel, and wood. Their tools could cut limestone. Wooden wedges and levers were also used in building the pyramids.
Sometimes up to 100,000 men worked for 20 seasons on one pyramid. More than 80 pyramids still stand today.

Hope that helped