Medieval Modern

A writer of historical fiction can describe medieval Paris. A science fiction writer can describe:

medieval Paris as covertly visited by time travelers, extraterrestrials, immortals, telepaths etc;

future or extraterrestrial cities that bear an uncanny resemblance to medieval Paris (!);

Paris as it might have been if feudal society had persisted into later centuries.

Keith Denison, aiming for Paris 1980 AD, arrives instead in Paris1980alpha AD. This is the chaos that the Time Patrol was guarding against:

narrow streets
high-peaked walls
women with covered heads in dark, long gowns
men in long coats and baggy trousers
smoke
barnyard smells
mounted, blue-uniformed troopers or policemen with unfamiliar firearms
civilians shouting, "sorcier!" and "juif vengeur!," crossing themselves and praying
language a mixture of French and English, with a different accent
centuries-old, half-timbered houses with leaded windows
horse-drawn wagons and carriages
barges pulled by rowboats
a mountainous alternative Notre Dame, like a Christian ziggurat
the troopers who arrest Denison hand him over to the Inquisition...

That is a good place to stop, especially since I do have other things to do!