Pyramid construction: How did the Egyptians build the pyramids?

The Great Pyramid of Giza, also known as the Pyramid of Khufu, is the oldest and largest of the three pyramids in the Giza Necropolis bordering what is now El Giza, Egypt. It is the oldest of the Seven Wonders of the Ancient World, and the only one to remain largely intact. Its sides climb at an angle of slightly less than 52 degrees, rising to a summit of 480 feet. But how did they manage to manoeuvre 2.5 tonne blocks to such an incredible height without the crane or the block and tackle system? It was a challenge to the ancient Egyptians and still remains a mystery to modern archaeologists.