
The Cour des Miracles was basically the biggest scam in Paris history
The Cour des Miracles was one of the poorest and most dangerous neighborhoods in Paris, mainly in the 17th century, basically a hideout for beggars, thieves, and criminals, where even the police were afraid to go in. During the day, these beggars would head out to the nicer parts of Paris pretending to be blind, crippled, or seriously sick, to get more money out of people passing by. Then at night, they'd come back to their own neighborhood, the actual Cour des Miracles, and that's where the "miracle" happened, the blind could suddenly see again, the crippled could walk fine. The name comes straight from that contrast, fake disabilities during the day, miraculous healing once they got home.
Victor Hugo actually made it famous in The Hunchback of Notre-Dame, there's a whole chapter set there, with Esmeralda getting dragged in and Clopin Trouillefou ruling over the place like a king.
There were several of these "courts" scattered around Paris, including one near what's now the Montorgueil area. Louis XIV eventually sent the police to clean the place out in the 1660s, under Gabriel Nicolas de la Reynie, and the whole area disappeared later during Haussmann's renovations in the 19th century. The expression "une cour des miracles" is still used in French today to describe a chaotic or sketchy place.