This lecture delves into the concept of the avant-garde in architecture, exploring its historical roots and ideological implications. It covers the avant-garde movements of the 20th century, from Futurism to Deconstructivism, and analyzes Manfredo Tafuri's perspective on the avant-garde as a progressive, regressive, and reformist ideology. The discussion also includes a detailed examination of Tafuri's seminal work 'The Sphere and the Labyrinth', which traces the evolution of avant-gardes in architecture from Piranesi to the 1970s, shedding light on the cultural and political significance of these movements.