Asia and Africa

Great Wall of China Defensive frontier and world heritage site, c.2400km (1500mi) long, extending from the Huang Hai (Yellow Sea) to the Central Asian Desert, n China. It is an amalgamation of fortifications constructed by various dynasties. The Warring States built the first sections of the wall. In 214 bc, Qin Shihuangdi ordered that they should be joined to form a unified boundary. The present wall was mostly built 600 years ago by the Ming dynasty. It averages 7.6m (25ft) high, and is up to 9m (30ft) thick.

pyramid The true pyramid exists only in Egypt, though the term has also been applied to similar structures in other countries. Egyptian pyramids are square in plan and their triangular sides, which directly face the points of the compass, slope upwards at approximately a 50° angle from the ground and meet at an apex. The prototype for the pyramid are the mastabas of the Old Kingdom (2680-2565 BC), which are rectangular in plan and have only two sloping sides. After these came the step-pyramid at Sakkara , built c.2620 BC, which soon evolved into the straight-sided true pyramid. This monumental structure was developed around the IV dynasty and continued to be the favored form for royal burial through the VI dynasty. Each monarch built his own pyramid in which his mummified body might be preserved for eternity away from human view and sacrilege. As a result of the lack of sophisticated machinery, the construction of each pyramid took many years and required measureless amounts of building materials and labor. Entrance into a pyramid is through an opening in the northern wall. A small passage, traversing lesser chambers, leads to the sepulchral room deep beneath the surface. Stone blocks forming a gable divert the weight of the great masonry masses over these chambers. Though the pyramids were usually built of rough stone blocks laid up in horizontal courses, many were constructed of mud bricks with a stone casing. The three pyramids of Giza near Cairo, all of the IV...