That's amazing! How did they build them exactly? I've heard many stories about using slaves and even aliens helping them! Yes, I've heard the one about aliens too! A pyramid is not hard to build, if you have plenty of cheap workers available. First they built a small mastaba-style tomb on the ground, in the ordinary way. Then one theory is that they heaped up tons and tons of dirt over the tomb, leaving a tunnel to the outside. Then they began placing huge stones all over the outside of the pyramid. To raise the stones to the top of the pyramid, they built long ramps of dirt and then rolled the stones up them. They kept making the ramps higher and longer. When it was done, they took the earth ramps away again. Still, it is unbelievable how they built such massive structures without machinery.