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)

A model wears a floral head dress as she promotes a chain of garden centres at the Royal Horticultural Soceity's Chelsea Flower Show in London, Britain, May 18, 2015. (Photo by Toby Melville/Reuters)

A Rohingya migrant woman, who arrived in Indonesia by boat, carries a bottle of drinking water inside a temporary compound for refugees in Kuala Cangkoi village in Lhoksukon, Indonesia's Aceh Province May 17, 2015. (Photo by Reuters/Beawiharta)

A young woman cools herself in a fountain in Budapest, Hungary July 6, 2015. Over the weekend, a heat wave has reached Hungary with temperatures topping 38 degrees Celsius (100.4 degrees Fahrenheit). (Photo by Laszlo Balogh/Reuters)

Actor George Clooney is arrested with his father Nick Clooney (2R) during a demonstration outside the Embassy of Sudan March 16, 2012 in Washington, DC. United to End Genocide, the Enough Campaign and Amnesty International held a rally to call on the United States and world leaders to stop the violence in South Sudan and prevent hundreds of thousands of people from starving. (Photo by Win McNamee/Getty Images)

In this photo made late Saturday, August 9, 2014, in Keelung, Taiwan, a traditional Chinese dance troupe performs during a parade marking the beginning of the Chinese folklore's mid-summer's Ghost Month Festival. Fourteen days into the seventh month of the lunar calendar, August 9, in 2014, marks the traditional Chinese Ghost Month where the gates of the underworld are opened and spirits of the deceased are set free to roam the world of the living. The month long festivities are aimed to please the roaming spirits. (Photo by Chiang Ying-ying/AP Photo)

Man prepares wigs as he waits for customers in downtown Johannesburg, on August 5, 2014. Some estimates put Africa's dry hair industry at as much as $6 billion a year; Nigerian singer Muma Gee recently boasted that she spends 500,000 naira ($3,100) on a single hair piece made of 11 sets of human hair. (Photo by Siphiwe Sibeko/Reuters)

“Elat’ma, the Ryazan Oblast region of Russia. This small town is only 300 kilometers (186 miles) from modern Moscow but remains 60 years in the past, dominated by the spirit of socialism. The air of the communist ‘50s can be seen in the town’s architecture, celebrations and other occurrences. But neither its beauty nor its ties to a socialist past brought photographer Anastasia Rudenko to this village. Elat’ma is unique in that it functions as a town for mentally disabled people”. – Michelle Cohan via CNN. (Photo by Anastasia Rudenko)