View of Maiji Mountain Grottoes in Tianshui, Gansu

Aerial photo taken on April 29, 2022 shows a view of the Maiji Mountain Grottoes in Tianshui, northwest China's Gansu Province. The Maiji Mountain Grottoes is one of the four most famous grottoes in China. (Xinhua/Chen Bin)

Aerial photo taken on April 29, 2022 shows a view of the Maiji Mountain Grottoes in Tianshui, northwest China's Gansu Province. The Maiji Mountain Grottoes is one of the four most famous grottoes in China. (Xinhua/Chen Bin)

Aerial photo taken on April 29, 2022 shows a view of the Maiji Mountain Grottoes in Tianshui, northwest China's Gansu Province. The Maiji Mountain Grottoes is one of the four most famous grottoes in China. (Xinhua/Chen Bin)

Aerial photo taken on April 29, 2022 shows a view of the Maiji Mountain Grottoes in Tianshui, northwest China's Gansu Province. The Maiji Mountain Grottoes is one of the four most famous grottoes in China. (Xinhua/Chen Bin)

Aerial photo taken on April 29, 2022 shows a view of the Maiji Mountain Grottoes in Tianshui, northwest China's Gansu Province. The Maiji Mountain Grottoes is one of the four most famous grottoes in China. (Xinhua/Chen Bin)