Tanzania is the home of the 40 kilometre-long Oldupai Gorge, the world famous palaeoanthropological site studied for more than 40 years by the Leakey family.
Olduvai is a mispronunciation of Oldupai, the Masai word for a type of wild sisal found around the gorge. The Gorge was re-named in 2005 to correct this mistake.
It is located at the border of the Ngorongoro conservation area and the Serengeti National Park. Oldupai has yielded numerous fossil remains from pliocene to pleistocene times (from about five million to 10.000 years ago), including the skull of the primitive hominid australopithecus boisei or nutcracker man, a species that became extinct about one million years ago. Despite the controversy surrounding the interpretation of many of the Oldupai specimens, scientists agree that no other site has produced stone tools, animal bones and early hominid remains so precisely associated in such a well understood environment. The 3.75 million year old fossilised footprints, found by Dr. Mary Leakey in 1975 at nearby laetoli, proved that our prehuman ancestors walked in a upright position, this is widely thought to rank among the greatest palaeoanthropogical discoveries of the past century. There are also several other important mid-pleistocene sites in the southwest of Tanzania, while the later quaternary sites of ndutu, eyasi, and ngaloba, all located within reach of Tanzania's Northern Circuit, have yielded significant fossil evidence for dating the evolution of homo sapiens. It was from this evidence that a group of American scientists recently concluded that anatomically modern humans actually evolved in East Africa.
Sites of significant historical importance from later years include the numerous medieval ruins scattered along Tanzania's 800-kilometre coastline. These are the remains of the Swahili city states that flourished on the East African coast between the 9th and 16th centuries. Among the most outstanding of these ruined medieval cities is the ancient Islamic trading centre of Kilwa Kiswani, which is located in the southwest of the country. Kilwa derived its wealth from the gold and ivory trade. By the end of the 14th century Kilwa boasted the largest stone building and mosque in Sub-Saharan Africa as well as the first mint on African soil. In 1312 a famous Arab traveller described Kilwa as the best built settlement he had ever seen. Another writer called it the Pearl of Africa. Other ruined cities dating from the same period include Songo Mnara, Mtitimira, Sanje Ya Kati and Sanje Majoma, near to Kilwa: Kunduchi: Mbweni, near Dar es Salaam and Kaole near to Bagamoyo. The former slave trading town of Bagamoyo - whose name comes from the Kiswahili meaning "lay down your heart" - and the town of Kilwa Kivinje in the south, are rich in late 19th and early 20th century German and British colonial architecture. In terms of human activity, Tanzania is also home to fine examples of prehistoric rock art some dating back about 50.000 years. There are more than 500 such sites known to exist in the central highlands alone, although much of the area remains unexplored. A string of early iron age sites in the Kagera region of northwest Tanzania provides evidence that complex metallurgical skills, involving the production of carbon steel, were in use almost 2000 years before such methods were developed in the west.