During the 1920s, the Catalan Josep Puig i Cadafalch (Barcelona, 1867–1956) and the Romanian Nicolae Iorga (Bucharest, 1871–1940), both medieval (art) historians and leading politicians in their respective countries, collaborated intensely. They helped each other in laying the intellectual foundations in their respective nation-building projects; Puig, for example, working on Moldavian churches and Iorga (and his disciples) on the Crown of Aragon. This little-known Catalano-Romanian collaboration should be seen as a form of a “transnationally produced national history,” and as such, it challenges the widespread view that national history is disinterested in this kind of intellectual exchanges with foreign colleagues. Puig’s exchanges in Romania also helped build his argument on the modernity of Catalan Romanesque, which he then transferred to the modern Catalan identity in the making. These views also permeated his interventions in Barcelona’s urban grid, which sought to imprint the cultural specificity that, according to him, was lacking in the Cerdà Plan (1859).