Atar is a town in northwestern Mauritania, the capital of the Adrar Region and the main settlement on the Adrar Plateau. It is home to an airport, a museum and a historic mosque, constructed in 1674. As of 2000 it had a population of 24,021. Today, the Atar is best known to outsiders as an entryway for tourists to visit the ruins of the ancient Moorish cities of Ouadane and Chinguetti. It was a key stop in the World's longest off-road race, the Paris Dakar Rally, held every January.
While the city sits within the Sahara Desert, a nearby water supply of considerable size was recently discovered. An underground river was discovered by Russian scientists using geoinformation to study the topography of the desert with satellites. They were operating at the request of the Mauritanian government. The find has been confirmed by the Mauritanian military. Eventually, the river will provide water enough to support Atar's entire population. . The Terjit oasis is near Atar.