This paper looks at the Belgrade Trilogy (1964) of Yugoslav-Croatian alternative filmmaker and experimental visual and performance artist Tomislav Gotovac. The works Straight Line, Circle, and Blue Rider, filmed in the nonprofessional environment of the Academic Kino Club, can be defined as visionary protostructural cinema. The chapter provides a close reading of the films, placing them at the intersection of avant-garde and documentary forms. In doing so, it unearths wide-ranging and transnational textual reference points across all films, spanning American pop culture and allusions to canonical works of art and cinema. Additionally, the chapter provides a mapping of Belgrade’s distinct ideological and sociopolitical realities embedded in the films, connecting these elements to the historical avant-garde film genre of the “city symphony.”