This combination photo shows tourists visiting the Ruins of St. Paul's complex in Macao, south China (top, photo by Tang Mengzong, archived on Nov. 11, 1986) and tourists visiting the same place on Oct. 8, 2019 (bottom, photo by Cheong Kam Ka). On Dec. 20, Macao will celebrate the 20th anniversary of its return to motherland. Over the past two decades, the special administrative region has made great strides in economic development and achieved prosperity and stability under the "one country, two systems" principle. (Xinhua)