The nineteenth century was, for the city walls of Rome, a period of major material and immaterial transformations which can be explored further by analysing the representations of the walls themselves. This article investigates the way in which landscape painters, scholars, topographers, architects and soldiers perceived the walls through the images they produced, and how this perception had an impact on their conservation. The walls were the only imperial building that, until 1870, retained its original function, but they were already mainly depicted as a ruin. The itinerary unfolds between 1821, when the perspective views of Sir William Gell were published, to the publication of Forma Urbis Romae by Rodolfo Lanciani (1893-1901), which became the basis for subsequent representations of the city, definitively conditioning the perception and representation of ancient Rome.
