Qingming Festival, or Tomb-Sweeping Day, fell on April 4 this year. It is a traditional Chinese festival during which people pay tribute to the dead and worship their ancestors. The holiday also provides a short break for China's residents to engage in outdoor activities or go sightseeing.

The grottoes were first built in AD 493. In the 14 centuries that followed, rulers of different dynasties and numerous pilgrims kept expanding their scale. There are currently more than 2,300 caves and niches on the steep cliffs of two hills flanking the Yihe River.