Pyramids were built by numerous Human Earth cultures as monuments, burial sites, and places of worship. They were part of the city designed by Kukulkan. All of the ancient Human cultures influenced by Kukulkan built some type of pyramid, although none of them did it in the perfect way that he had planned. (TAS: "How Sharper Than a Serpent's Tooth")
The series of monumental burial chambers built for Egyptian kings of Earth, are among the oldest known, dating from the 27th century BC. The Great Pyramid of Giza was the largest of the pyramids, and one of Earth's most notable landmarks. It had been observed by anthropologists, following proper time travel protocols, since 2769. Daniels showed temporal observers watching the pyramid's construction to Captain Archer in the Temporal Observatory. (ENT: "Cold Front")
Another prominent pyramid-shaped structure on Earth was the Transamerica Pyramid.