Tiantishan Grottoes in Wuwei county of Gansu province [Photo provided to chinadaily.com.cn]

The Tiantishan Grottoes in central Gansu province's Wuwei county were dug about 1,600 years ago. 

Tianti means "ladder to the sky" and shan means mountain. The site is a honeycomb of 17 caves in three layers.

It houses a 15-meter-high Sakyamuni statue and smaller peripheral caves and murals.

Experts have collected some of the site's relics for restoration. The local government built a 10-meter-high dam to protect the caves from water damage.