Photo taken on Sept. 6, 2020 shows water infiltration detectors set inside a cave of the Maiji Mountain Grottoes in Tianshui, northwest China's Gansu Province. With 221 existing caves, the Maiji Mountain Grottoes contain more than 10,000 clay sculptures which were made as early as 1,600 years ago. Conservation efforts at the grottoes started in the 1980s and have been bolstered by modern technologies such as the Internet of Things (IoT) and sensors. (Xinhua/Geng Xinning)
