146.6 mètres!
The Great Pyramid of Giza is the largest of the pyramids at Giza, in Egypt, built for King Khufu about 4,600 years ago. When it was finished, it stood about 147 meters (481 feet) tall, measured straight up from the middle of its base to its peak. Its peak and most of its smooth outer stones are now gone, so it is shorter today.
Because the peak is missing, the pyramid's original height cannot be measured directly. It is worked out instead from the width of the base and the slope of the faces. From 1880 to 1882, the archaeologist Flinders Petrie measured both. He found each side of the base to be about 230.3 meters (756 feet) long, and the faces to slope at about 52 degrees.
From these, Petrie calculated an original height of 5,776 inches, or 146.7 meters. Harvard University's Giza Project gives the same height to the nearest foot, 481 feet (146.6 meters). The sides of the base are very nearly equal: Petrie found that no two differed in length by more than 4.5 centimeters (1.8 inches).
The explorer measures the pyramid's height, but the pyramid is wider than it is tall. Each side of its base is about 1.6 times its original height.
The Great Pyramid was built for Khufu, also known as Cheops, a king of Egypt's Fourth Dynasty. That was during the Old Kingdom, a period of strong central government. Harvard's Giza Project dates the pyramid to around 2550 BCE, meaning 2550 years before the Common Era.
Khufu's successors built the two other large pyramids at Giza. Archaeologists at Ancient Egypt Research Associates date all three to a span of about 85 years, between 2589 and 2504 BCE. They describe the Great Pyramid as the largest pyramid ever built, and the only one of the Seven Wonders of the Ancient World still standing.
The pyramid is estimated to contain about 2.3 million blocks of stone, with a total volume of about 2.6 million cubic meters. The blocks are often said to weigh about 2.5 short tons (2.3 tonnes) each on average, but they vary widely in size and shape. Much of the stone probably came from a quarry close by, on the pyramid's south side, cut as deep as 30 meters (98 feet) into the rock.
When new, the pyramid was covered in a smooth casing of white limestone, about 85,000 square meters (21 acres) of it. Most of the casing was carried away for building stone in the Middle Ages, exposing the rougher blocks underneath. A few casing stones still remain at the base.