In episode 19 of Toaru Kagaku no Railgun S, Saten is shown reading a book to Febri, presumably as a bedtime story.
In the heart of a certain country, there stood buildings altogether too splendid.
They were built from solid stone, much of which was beautifully decorated. They invariably had peaked roofs and stone figures of strange animals that drew the eye. They stood side-by-side in an orderly manner, within their orderly city blocks.
The roads were so wide that ten cars could drive in parallel, and they intersected at perfect right angles. Vehicles would kick up a thin cloud of dust as they drove. They were tiny by comparison with the grandeur of the city.
And there was nobody there. Neither people nor vehicles.
Kino stopped his Hermes in the middle of an intersection and looked all around.
The buildings silently flowed towards the waterfront as new buildings emerged to take their place, and then those new buildings too flowed away. Beyond them was nothing but the unchanging blue sky.
The first line does not appear anywhere on the internet, so it doesn't look like this is pre-existing Japanese fiction. It could be pre-existing non-Japanese fiction that has been translated into Japanese for the first time (or differently) by somebody involved in the production of Railgun S. Alternatively, it could be original Japanese fiction.