Archaeological site on the eastern Serengeti Plain, northern Tanzania. It is a steep-sided ravine about 30 mi (48 km) long and 295 ft (90 m) deep. Deposits exposed in the sides of the gorge cover a time span from circa 2,100,000 to 15,000 years ago and have yielded the remains of more than 50 hominins as well as the most complete sequence of stone tool industries. The site first came to public notice in 1959 when Louis and Mary Leakey (see Leakey family) uncovered the first specimens of Paranthropus, a hominin related to Australopithecus. Remains of Homo habilis, Homo erectus, and Homo sapiens have since been found. These discoveries have strengthened the argument that the human lineage originated in Africa. Seealso stone tool industry; Oldowan industry.

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The Porta Westfalica is a gorge, where the Weser river runs through the passage between the mountain chains of the Wiehengebirge in the west and the Wesergebirge (part of the Weserbergland) in the east. It is located in the district of Minden-Lübbecke in North Rhine-Westphalia, Germany.

Since 1973 Porta Westfalica is also the name of a town, which was established by merging fifteen villages surrounding the gorge.

The name "Porta Westfalica" is Latin language term, and means "Gate to Westphalia". Coming from the north, the gorge is the entry to the region of Westphalia. Despite the Latin name the term was not coined in Roman times, but by scholars of the 19th century.

High above the gorge on the west side is a large six-sided stone structure that can be seen from a considerable distance; this is the Emperor William Memorial, erected in honour of Kaiser Wilhelm I and dedicated in 1896.