White Nights have become a common symbol of Saint Petersburg, Russia, where they occur from about 11 June to 2 July, and the last 10 days of June are celebrated with cultural events known as the White Nights Festival.
It’s because this place, the sun remains less than 6 or 7 degrees below the horizon south of the Arctic Circle.
So this place occurs midnight twilight instead of midnight sun, so that daytime activities, such as reading, are still possible without artificial light on a clear night.