"The Day of Forever" is a 1966 science fiction short story by J.G. Ballard, which was published in the anthology of the same title.
Setting
The events of the story unfold on Earth at some undisclosed era in the future when the planet has ceased to rotate, hence the opening line, "At Columbine Sept Heures it was always dusk."
References
The Day of Forever (short story) Wikipedia(Text) CC BY-SA