Tour Saint-Jacques

"This tower is the only remnant of a church, the original Saint-Jacques-de-la-Boucherie (Saint Jacques of the Butchery), owing its name and function to the foundation of a chapel by the Confederation of Butchers in the 12th century. The main body of the church disappeared towards the end of the 18th century when it was destroyed, and its stones sold."

https://a-fab-journey.com/tour-saint-jacques-paris-secret-stairway-to-heaven/