This combination photo shows a view of the Ponte de Amizade (Bridge of Friendship) in Macao, south China (top, photo by Tang Mengzong, archived on Dec. 31, 1995) and the Hong Kong-Zhuhai-Macao Bridge seen from Macao, south China on Oct. 22, 2018 (bottom, photo by Yin Bogu). 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. Since Dec. 20, 1999, the historic day for Macao, what has changed? And what remains unchanged? Our selection of photos present comparative illustrations of the south China city's past and present. (Xinhua)