In ancient history:

Ancient monumental structure constructed of or faced with stone or brick and having a rectangular base and four sloping triangular sides meeting at an apex. Pyramids have been built at various times and places; the best-known are those of Egypt and of Central and South America. The pyramids of ancient Egypt were royal tombs. Each contained an inner sepulchral chamber that housed the deceased (usually mummified) ruler, members of his entourage, and artifacts. The rest of the pyramid complex consisted of a large enclosure, an adjacent mortuary temple, and a causeway leading down to a pavilion. About 80 royal pyramids survive in Egypt, the greatest being those at Giza. American pyramids include the pyramids of the Sun and Moon at Teotihuacán, the Castillo at Chichén Itzá, and various Inca and Chimú structures in Andean settlements. These pyramids were generally built of earth and faced with stone; they are typically stepped pyramids and are topped by a platform or temple structure used for rituals, including human sacrifice. 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 B.C.), which are rectangular in plan and have only two sloping sides. After these came the step-pyramid at Sakkara, built c.2620 B.C., 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. Source: http://www.answers.com/pyramids?initiator=IE7:SearchBox

Egyptians