When one's nature travel plans lead them to Tanzania, a safari is almost certainly on their mind. Some travelers also devote time during their Kenya and Tanzania safari taking in landmarks that dot the nation. For vacationers who want to marvel at both the local wildlife and natural wonders of Tanzania, a stop at Olduvai Gorge is a must.

Located in the Great Rift Valley, Olduvai Gorge is a steep-sided ravine that stretches through the Eastern Serengeti Plains. Deposits that line the sides of the ravine date as far back as 2.1 million years and have yielded fossil remains of more than 60 human ancestral species, earning the site designation as "the cradle of mankind."

These findings have provided the most contiguous record of human evolution during the past 2 million years as well as the development of stone tools. This information didn't escape the attention of the United Nations, which declared the Gorge a UNESCO World Heritage Site in 1979.

One of the more interesting geological formations in the area is the Olduvai Gorge monolith, as a series of rocky protrusions that rise from the earth in an impressive site that even inspired parts of science fiction author Arthur C. Clarke's 2001: A Space Odyssey book series.

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