shí kū
rock cave
grotto
cliff caves (often with Buddhist statues)
Lóng mén shí kū
Longmen grottoes at Luoyang 洛陽|洛阳[Luo4 yang2], Henan
Yún gāng shí kū
Yungang caves at Datong 大同, Shanxi 山西
Dūn huáng shí kū
Dunhuang caves in Gansu
refers to Mogao caves 莫高石窟[Mo4 gao1 shi2 ku1]
Mài jī shān shí kū
Mt Maiji caves at Tianshui 天水, Gansu
sì dà shí kū
Four great caves, namely: Longmen grottoes 龍門石窟|龙门石窟[Long2 men2 shi2 ku1] at Luoyang, Henan, Yungang caves 雲岡石窟|云冈石窟[Yun2 gang1 shi2 ku1] at Datong, Shanxi, Mogao caves 莫高窟[Mo4 gao1 ku1] at Dunhuang, Gansu, and Mt Maiji caves 麥積山石窟|麦积山石窟[Mai4 ji1 shan1 shi2 ku1] at Tianshui, Gansu