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)

In this May 1, 2016 photo, a reluctant donkey is alternately pushed and pulled and enticed with carrots toward town hall in order to be dressed for the costume competition at the annual donkey festival in Otumba, Mexico state, Mexico. Otumba was an important donkey market during Spanish colonial times, standing at the crossroads of major roads leading to Mexico City, where the beasts pulled heavy loads and carried travelers. Today, however, farmers use tractors and pickup trucks, and the donkey population is in decline. (Photo by Rebecca Blackwell/AP Photo)

Protester Lauren Digioia wears police tape during an Occupy Wall Street protest in Union Square on March 19, 2012 in New York City. Protesters affiliated with the movement are gathering in Union Square today following 73 arrests at a six-month anniversary rally at Zuccotti Park over the weekend. (Photo by Mario Tama/Getty Images)

The unromantic gypsies. Children boxing in a gypsy camp in Kent, England on July 1, 1951. Like all boys these gypsy lads like to try their hand at boxing. Encouraged by their friends they fight it out on Corke's Meadow. Few Romanies now live a life of wandering romance. Most are like the three hundred squatters of Corke's Meadow, Kent, which is part of a “gypsy problem” that involves about 100,000 today. Of those about 25,000 can be rightly called gypsies, the rest are Mumpers and Posh-rats and Hobos. Corke's Meadow has both kinds. “Picture Post” cameraman Bert Hardy photographs the Corke's Meadow gypsies in their encampment. (Photo by Hulton-Deutsch Collection/Corbis via Getty Images)

14 week-old twin polar bear cubs play during their first presentation to the media in Hellabrunn zoo on March 19, 2014 in Munich, Germany. The male and female twins were born on December 9, 2013 in the zoo. (Photo by Alexandra Beier/Getty Images)

“Titanoboa is a genus of snake that lived approximately 58–60 million years ago, during the Paleocene epoch, a 10-million-year period immediately following the dinosaur extinction event. The only known species is the Titanoboa cerrejonensis, the largest snake ever discovered, which supplanted the previous record holder, Gigantophis”. – Wikipedia

Photo: Leah Del Rio views a replica of the prehistoric Titanoboa, the largest snake to ever live, on display at Grand Central Terminal on March 23, 2012 in New York City. (Photo by Michael Loccisano/Getty Images)