Tassili n'Ajjer the most Mysterious place on Earth. Tassili n'Ajjer (Berber: Tasili n Ajjer, Arabic: طاسيلي ناجر‎; "Plateau of the Rivers") is a national park in the Sahara desert, located on a vast plateau in south-east Algeria. Having one of the most important groupings of prehistoric cave art in the world, and covering an area of over 72,000 km2 (28,000 sq mi), Tassili n'Ajjer was inducted into UNESCO's World Heritage Site list in 1982. The rock formation is an archaeological site, noted for its numerous prehistoric parietal works of rock art, first reported in 1910, that date to the early Neolithic era at the end of the last glacial period during which the Sahara was a habitable savanna rather than the current desert. Although sources vary considerably, the earliest pieces of art are assumed to be 12,000 years old. The vast majority date to the 9th and 10th millennia BP or younger, according to OSL dating of associated sediments. Among the 15,000 engravings so far identified depicted are large wild animals including antelopes and crocodiles, cattle herds and humans that engage in activities such as hunting and dancing. According to UNESCO, "The exceptional density of paintings and engravings...have made Tassili world famous.