Wall of the Farmers-General

The Wall of the Ferme générale was commissioned by Antoine Lavoisier and built between 1784 and 1791 by the Ferme générale (General Farm), the corporation of tax farmers. It was one of the several city walls of Paris built between the early Middle Ages and the mid 19th century. It was 24 kilometers long and roughly followed the route now occupied by line 2 and line 6 of the metro. It crossed the districts of the Place de l'Étoile, Batignolles, Pigalle, Belleville, Nation, the Place d'Italie, Denfert-Rochereau, Montparnasse and the Trocadéro.

Unlike earlier walls, the Farmers-General Wall was not intended to defend Paris from invaders but to enforce the payment of a toll on goods entering Paris ("octroi") to the Ferme générale. The wall's tax-collection function made it very unpopular: a play on words of the time went "Le mur murant Paris rend Paris murmurant" ("The wall walling Paris keeps Paris murmuring") There was also an epigram:

Pour augmenter son numéraire (To increase its cash)

Et raccourcir notre horizon (And to shorten our horizon),
La Ferme a jugé nécessaire (The Ferme générale judges it necessary)
De mettre Paris en prison (To put Paris in prison).

Architect Claude Nicolas Ledoux designed its 62 toll barriers in a neo-classical or even classical style. The architecture of the buildings, "dens of the Tax Department metamorphosed into palaces with columns" according to Louis-Sébastien Mercier, highlighted the oppression which the wall represented for Parisians. The wall was bordered by a boulevards outside and a chemin de ronde (a raised protected walkway) inside, except between the barrière d'Italie (now the Place d'Italie) and the barrière d’Enfer (now the Place Denfert-Rochereau) where Gobelins, Saint-Jacques and d'Enfer replaced the chemin de ronde inside the wall.

...
Wikipedia