It is already one of the world’s most iconic cities, but this incredible collection shows how much Paris has changed over the course of the past century. The collection, by French photographer Julien Knez, shows Paris in the 1940s against a backdrop of how the same places look today. Knez says he put the striking collection together to celebrate the 71st anniversary of the city’s liberation from Nazi control in August 1944. Here: Soldiers outside the Hotel De Ville in the 1940s. (Photo by Julien Knez/Caters News)

Uniformed participant dance during a mass rally and parade in the capital's main ceremonial square, a day after the ruling party wrapped up its first congress in 36 years by elevating him to party chairman, in Pyongyang, North Korea, May 10, 2016. (Photo by Damir Sagolj/Reuters)

In this February 7, 2014 file photo, Matt Figi hugs and tickles his once severely-ill seven year old daughter Charlotte, as they walk together inside a greenhouse for a special strain of medical marijuana known as Charlotte's Web, which was named after the girl early in her treatment for crippling severe epilepsy, in the mountains west of Colorado Springs, Colo. Colorado is poised to award more than $8 million for medical marijuana research, a step toward addressing complaints that little is known about pot's medical potential. Among the research projects poised for approval on Wednesday, December 17, 2014, are one for pediatric epilepsy patients, and another for children with brain tumors. (Photo by Brennan Linsley/AP Photo)

A full size working replica of the pink limousine used by Parker to chauffeur Lady Penelope in Gerry Anderson's television series “Thunderbirds”, unveiled at Woburn Abbey. United Kingdom, 27th May 1968. (Photo by Jim Gray/Keystone/Getty Images)

This restroom on the rubbly flanks of Jonsknuten in Norway looks up at the peak of the 904m mountain. Yu have to leave the door open to enjoy the view but the chances of being disturbed are minimal. (Photo by Olaf Menz/Lonely Planet)

When it opened in 1955, the Grande Hotel in the Indian Ocean city of Beira was one of the most luxurious in Africa. Photojournalist Fellipe Abreu documents the lives of the 3,500 people who now fill this long-closed hotel to capacity. (Photo by Fellipe Abreu/The Guardian)

A flock of sheep huddles together while snow spindrift is whipped up by strong winds in Swaledale, North Yorkshire, UK on March 17, 2017. (Photo by Paul Kingston/NNP North News & Pictures Ltd)

U.S. President elect Barack Obama kisses his wife Michelle as Vice-President elect Joe Biden (right) embraces his wife Jill after Obama gave his victory speech during an election night gathering in Grant Park on November 4, 2008 in Chicago, Illinois. (Photo by Scott Olson/Getty Images)