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)

Mike De Butts adds the finishing touches to a giant Baobab Tree sculpture entitled “Under the Baobab”, outside the Southbank Centre on May 24, 2012 in London, England. The Pirate Technics' installation is made from a selection of brightly coloured fabrics from around the world, and is part of the Southbank Centre's “Festival of the World” exhibition, which includes a series of large scale pieces of art that will be in place around the Southbank centre over the Summer. (Photo by Dan Kitwood)

Residents observe a police officer take up position during an operation at the Mare slums complex in Rio de Janeiro March 25, 2014. The federal troops have taken control of security operations in Mare slums complex to help quell a surge in violent crime following attacks by drug traffickers on police posts in three slums on the north side of the city, government officials said. (Photo by Ricardo Moraes/Reuters)

Members of the Cyclophonica band play instruments as they make a stop during a ride in Rio de Janeiro May 17, 2015. The Cyclophonica band was formed by a group of musicians riding bicycles around the city, mixing sport and culture and entertaining people on the streets, according to its founder Leonardo Fuks. (Photo by Pilar Olivares/Reuters)

Andrea Abarca, (C) leads an aerobics class in Los Guidos de Desamparados July 23, 2015. More than 300 women participated in a physical health program organized by Abarca, which aims to combat obesity and sedentary behavior in poor women living in a slum. The National Nutrition Survey shows that the Costa Rican population has 62.4 percent of adult men who are obese, while among women the percentage was 77.3, according to local media. (Photo by Juan Carlos Ulate/Reuters)

Fan Bing Bing, Concha de Plata (Silver Shell) award winnerfor best actress for the feature film “I Am Not Madame Bovary” speaks on her telephone during the awards ceremony at the San Sebastian Film Festival, September 24, 2016, in San Sebastian, northern Spain. (Photo by Vincent West/Reuters)

A woman from a group called “Las Patronas” (The bosses), a charitable organization that feeds Central American immigrants who travel atop a freight train known as “La Bestia”, passes food and water to immigrants on their way to the border with the United States, at Amatlan de los Reyes, in Veracruz state, Mexico October 22, 2016. (Photo by Daniel Becerril/Reuters)

Firefighters work to quell a fire on an alleged clandestine gasoline storage in the Ixtlahuaca community, Mexico on January 5, 2016. Looting broke out at dozens of stores in Mexico on Wednesday on the sidelines of protests against a steep gasoline price increase as authorities detained more than 200 people. (Photo by Mario Vazquez de la Torre/AFP Photo)