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)

Burundian refugees gather on the shores of Lake Tanganyika in Kagunga village in Kigoma region in western Tanzania with their belongings, as they wait for MV Liemba to transport them to Kigoma township, May 17, 2015. Burundi's embattled President Pierre Nkurunziza sacked his defense and foreign ministers on Monday, five days after surviving an attempted coup by generals opposed to his bid for a third term in office. (Photo by Thomas Mukoya/Reuters)

A humanoid robot works side by side with employees in the assembly line at a factory of Glory Ltd., a manufacturer of automatic change dispensers, in Kazo, north of Tokyo, Japan, July 1, 2015. Japanese firms are ramping up spending on robotics and automation, responding at last to premier Shinzo Abe's efforts to stimulate the economy and end two decades of stagnation and deflation. (Photo by Issei Kato/Reuters)

A man paddles a makeshift boat along a flooded street in Guasdualito, in the state of Apure, Venezuela, July 4, 2015. A total of 9,000 families have been affected by the overflowing of rivers Arauca and Sarare in Guasdualito, Apure state, because of the heavy rains in recent days in this area of the country, local media reported. (Photo by Carlos Eduardo Ramirez/Reuters)

A participant of the Castle Party festival poses for picture as a man walks past in Bolkow, southwestern Poland, July 16, 2015. The annual festival features around 50 musicians and artists playing on various stage Gothic rock and other styles of the dark music subculture. Outside Germany, it is one of the biggest festival with this genre of music, the event attracts regular international audience of up to 5000, the organizers said. (Photo by Kacper Pempel/Reuters)

A man wearing a Guy Fawkes mask enjoys a ride on a 350-meter (1148 feet) long water slide during 2015 City Silde Festa in central Seoul, South Korea, July 19, 2015. A 350 meter-long waterslide has been installed in downtown of Seoul, the longest waterslide to be recorded in Korea, according to local media. (Photo by Kim Hong-Ji/Reuters)

Romanian soldiers take part in a joint military exercise with NATO members, called “Agile Spirit 2015” at the Vaziani military base outside Tbilisi, Georgia, July 21, 2015. Georgian soldiers along with U.S. marines and platoon-size units from Bulgaria, Latvia, Lithuania and Romania are taking part in the exercises at the Vaziani military base outside Tbilisi. (Photo by David Mdzinarishvili/Reuters)

Residents make their way along a fence as they try to cross a flooded street after heavy rainfall hit Wuhan, Hubei province, China, July 23, 2015. Severe downpours hit the city on Thursday, flooding streets and shutting down public transportations, local media reported. (Photo by Reuters/China Daily)