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. Photo: Xinhua

This combination photo shows a view of Rua das Estalagens, one of the earliest streets in Macao (top, photo by Tang Mengzong, issued on Aug. 26, 1986), and a street view of Macao, south China on Sept. 27, 2019 (bottom, photo by Qin Qing). 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. Photo: Xinhua

This combination photo shows people watching a performance at Clube Militar (Military Club) in Macao, south China (top, photo by Bi Yuenian, archived on Aug. 4, 1993) and dancers performing on street during the International Youth Dancing Festival in Macao, south China on July 20, 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. 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. Photo: Xinhua

This combination photo shows an older image of the A-Ma Temple, a temple honoring the Chinese sea-goddess Mazu (top, photo by Bi Yuenian, issued on Aug.15, 1992), and the same religious complex in Macao, south China on April 2, 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. 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. Photo: Xinhua

This combination photo shows students having a culinary class at a tourism college in Macao, south China (top, photo by Zhang Ruiqi, issued on Aug. 4, 1993) and students cooking shrimps at Macao Institute for Tourism Studies in Macao, south China on March 11, 2014 (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. 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. Photo: Xinhua

This combination photo shows scouts participating in the "Walk for a Million" charity activity in Macao, south China (top, Xinhua, issued on June. 18, 1999) and scouts taking oaths in an anniversary celebration in Macao, south China on Oct. 9, 2011 (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. 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. Photo: Xinhua

This combination photo shows an aerial view of the Ruins of St. Paul's complex and its surroundings in Macao, south China (top, photo by Chen Demu, archived on Nov. 7, 1986) and an aerial view of the same area on Oct. 24, 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. 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. Photo: Xinhua

This combination photo shows people using telephone booths in Macao (top, photo by Bi Yuenian, archived on Sept. 2, 1994) and a local resident recording videos of a light installation show with a smartphone in Macao, south China on Feb. 12, 2016 (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. 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. Photo: Xinhua

This combination photo shows readers at the Octagonal Pavilion Library in Macao, south China (top, file photo, issued on June 18, 1999) and the same library on April 22, 2017 (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. 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. Photo: Xinhua

This combination photo shows readers at the Octagonal Pavilion Library in Macao, south China (top, file photo, issued on June 18, 1999) and the same library on April 22, 2017 (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. 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. Photo: Xinhua