Construction workers reinforce the cliff body of Mogao Grottoes, one of the country’s three major Buddhist art treasures, in Dunhuang city, Northwest China’s Gansu province, April 18, 2011. China has spent 10 million yuan (more than $1.5 million) on the maintenance of the grottoes since last year as weathering, cracking and even collapse are threatening the body of the relics. The Mogao Grottoes, or the Ancient Caves of 1,000 Buddhas, were listed in 1987 by the United Nations' Educational, Scientific, and Cultural Organization as China's first world heritage site. [Photo/Xinhua]