The fortifications of Paris in the 19th and 20th centuries comprise:The Thiers Wall, surrounding the city of Paris, and farther from the city, The detached forts and their complementary fieldworks.

The Wall of the Ferme générale was one of the several city walls of Paris built between the early Middle Ages and the mid 19th century. Built between 1784 and 1791, the 24 km wall crossed the districts of the Place de l'Étoile, Batignolles, Pigalle, Belleville, Nation, the Place d'Italie, Denfert-Rochereau, Montparnasse and the Trocadéro, roughly following the route now traced by line 2 and line 6 of the Paris Métro. The wall was demolished in the early 1860s, although elements of some of its gates remain.