About Giza
The Great pyramid was 145.75 m (481 ft) high. Over the years, it lost 10 m (30 ft) off its top. It ranked as the tallest structure on Earth for more than 43 centuries, only to be surpassed in height in the nineteenth century AD. It was covered with a casing of stones to smooth its surface (some of the casing can still be seen near the top of Khefre's pyramid). The sloping angle of its sides is 51 degrees and 51 minutes. Each side is carefully oriented with one of the cardinal points of the compass, that is, north, south, east, and west. The horizontal cross section of the pyramid is square at any level, with each side measuring 229 m (751 ft) in length. The maximum error between side lengths is astonishingly less than 0.1%.
The structure consists of approximately 2 million blocks of stone, each weighing more than two tons. It has been suggested that there are enough blocks in the three pyramids to build a 3 m (10 ft) high, 0.3 m (1 ft) thick wall around France. The area covered by the Great pyramid can accommodate St Peter's in Rome, the cathedrals of Florence and Milan, and Westminster and St Paul's in London combined.
On the north face, is the pyramid's entrance. A number of corridors, galleries, and escape shafts either lead to the King's burial chamber, or were intended to serve other functions. The King's chamber is located at the heart of the pyramid, only accessible through the Great Gallery and an ascending corridor. The King's sarcophagus is made of red granite, as are the interior walls of the King's Chamber. Most impressive is the sharp-edged stone over the doorway which is over 3 m (10 ft) long, 2.4 m (8 feet) high and 1.3 m (4 ft) thick. All of the interior stones fit so well, a card won't fit between them. The sarcophagus is oriented in accordance with the compass directions, and is only about 1 cm smaller in dimensions than the chamber entrance. It might have been introduced as the structure was progressing.