This Day in History: Mystery of the Pyramids unearthed

On January 12, 1984, an international panel overseeing the restoration of the Great Pyramids in Egypt overcomes years of frustration when it resorts to the method the ancient Egyptians employed to build the pyramids.
Restorers abandoned the modern construction techniques of mortar used in Giza pyramids, outside Cairo by early 1980 when the techniques proved even more destructive in the limestone blocks of the severely decayed manmade structures, the oldest on earth.
The project proceeded smoothly as soon as the interlocking blocks method used by the original pyramids builders was applied by the modern restorers.
The three enormous pyramids situated at Giza outside of Cairo were built by King Khufu, his son, and his grandson in the Fourth Dynasty. The largest, known as the Great Pyramid, was built by Khufu and is the only one of the “Seven Wonders of the World” from antiquity that still survives.
It is believed that construction of the pyramid took 20 years and involved over 20,000 workers, bakers, carpenters, and water carriers. The exact method in which this architectural masterpiece was built is not definitively known, but the leading theory is that the Egyptians employed an encircling embankment of sand, brick, and earth that was increased in height as the pyramid rose.
The ancient Egyptians built nearly 100 pyramids over a millennium to serve as burial chambers for their royalty as they believed the pyramids eased the monarchs’ passage into the afterlife.