But the director revealed that he initially did not consider shooting in the French city and travelled a number of places in search of the perfect location for the film.
"At first, we didn't necessarily think we were going to shoot there and we did explore other possibilities," Nolan said in a statement.
He, however, said when they discovered the original city they couldn't stop themselves from filming there.
"But seeing the reality of the place and the unique quality of its geography made it inevitable that we would film there, whatever the challenges might be. So we just dove in."
"It was really quite something shooting there. To this day there are reminders of the events of 1940 that show themselves all the time. When the tide is particularly low you can still see a shipwreck of a boat that went down right next to the mole. And buttons and buckles from soldiers' uniforms are still being found. It's really incredible," said "Dunkirk" producer Emma Thomas.