Olorgesailie is a Lower Palaeolithic archaeological site in southern Kenya on the floor of the Rift Valley. It was discovered in 1919 by John Walker Gregory, a British geologist. It is located about 70km south-west of Nairobi on the road to Magadi.
The site covering an area of 52 acres was donated to the government of Kenya by the Maasai community. The name ‘Olorgesailie’ draws from a nearby mountain Mt Olorgesailie which was named after a Maasai elder who would meditate and hold meeting with village elders up the mountain. It was gazetted as a national monument on June 6, 1970.
Excavation work in the region began in 1942 led by Dr Louis and Mrs Mary Leakey assisted by paroled Italian prisoners of war, and continued up to 1947. In the 1960s, Glynn Isaac, a South African archaeologist, carried out excavation work at Olorgesailie as part of his dissertation. From the 1980s to date research at Olorgesailie is being carried out by a team from the Smithsonian Institution led by Richard Potts in collaboration with the National Museums of Kenya.
The site is characterised by in situ displays of prehistoric materials including numerous hand axes and fossilized skeletons of extinct species of elephant, hippopotamus, zebra, giraffe and baboon. There are several butchering localities that have been discovered at Olorgesailie evidenced by concentrations of bone fragments and hand axes and other stone tools deposited along the shoreline of a now dried-up lake.
Olorgesailie is world renown as the “factory of stone tools” and is the only place in the world with the largest number of Acheulian stone tools made by hominids between about 600,000 and 900,000 years ago. It has preserved biological and cultural evidence about the evolution of man.
The site museum at Olorgesailie holds exhibits aimed at interpreting the prehistoric site on human evolution, stone tools and site formation.