Rising incongruously above the steppes of south-eastern Kazakhstan is a structure as famed for the myths that surround it as for the sound it produces - a single, singing dune.
Located between the folds of the Tian Shan mountains near the Chinese border, the dune, which is 150m high and 3km long, generates a low-pitched, organ-like rumble in dry weather.
Before physicists established that the sound came from sand grains rubbing against each other, legends about its origins abounded.
Among them was the legend claiming that the great Mongol conqueror Genghis Khan was buried beneath it.
The sand hill is one of the main attractions of the Altyn-Emel national park, which is located about 180km north-east of Kazakhstan's commercial hub Almaty.
Tourists, like the one standing at the edge of the dune, at the top right of the picture, are drawn to the region for the singing dune as well as the spectacular landscapes.
The park also features volcanic mountains, millennia-old burial sites of the rulers of the Saka, an ancient nomadic tribe, and numerous wild animals including goitered gazelles, which are known for their lightning-fast, bounding gait.