Rijeka, historically known as Fiume, represents the entangled histories of Adriatic border cities shaped by imperial legacies, nationalist projects, and ideological upheavals. Situated between Central Europe and the Mediterranean, the city has repeatedly experienced bordering, debordering, and rebordering—from its status as a Habsburg Corpus Separatum and imperial contact zone to the ephemeral Free State of Fiume (1920–1924), Fascist Italianization, and postwar incorporation into socialist Yugoslavia. Successive regimes imposed shifting territorial, linguistic, and symbolic frameworks, yet traditions of multilingualism, hybridity, and civic autonomy persisted. The occupation led by Gabriele D’Annunzio in 1919 anticipated Fascist aesthetics and underscored Rijeka’s role as a frontier laboratory of nationalist experimentation. After 1945, Yugoslav integration and the Italian exodus transformed its demographic and cultural landscape, while post-1991 independence and EU accession repositioned Rijeka as a “Port of Diversity.” Contemporary disputes over memory and urban regeneration projects affirm its ongoing status as a contested node of transnational entanglement.