E China's Zaozhuang back to eco-friendly city

People walk at the Donghu Park in Zaozhuang City, east China's Shandong Province, Sept. 15, 2017. Zaozhuang used to be one of the most important coal-mining cities of China. After years of economic restructuring and environmental remediation, Zaozhuang is back to an eco-friendly city. (Xinhua/Sun Zhongzhe)