About 180 km north-west of Dunhuang, on the edge of the Lop Nur basin, the Yardang Geopark is a vast field of wind-eroded sandstone formations — long parallel ridges and isolated towers shaped by the prevailing winds over hundreds of thousands of years. Some of the formations have been given names — "sphinx", "fleet of ships", "peacock" — and the bus that takes you through the park stops at the more photogenic ones.
The drive out is half the experience: four hours each way through pure desert, past Yumen Pass and the Han Great Wall, with not much in between but gravel plains and the occasional dust storm. Most travellers combine Yardang with the two passes in a long single day; if you can spring for an overnight stay in the park, the night skies are extraordinary. Best in spring and autumn — summer afternoons can hit 40°C with no shade.