I'm sorry to disagree with you on these topics. Catalonia has never really felt to be politically, culturally and linguistically part of Spain and indeed it never was. Its history shows several attempts at being an independent country, and in fact Catalonian culture can't be identified with Spanish one. There is a distinct and peculiar Weltanschauung which can be also seen in all its artists, more revolutionary than fascist.
During the Spanish Civil War Barcellona was the heart of the republican and revolutionary forces opposing Franco's nationalist army. A lot is said about it in Orwell's Homage to Catalonia. The place paid a heavy tribute of blood to its independence dream.
So Catalonia was everything but fascist. And they have always taken good care to stress their differences from Spain.
Modernist is the term for Liberty, Jugendstil and Art Nouveau in Spain, but is not the Modernism or Rationalism or Art Déco as it is intended elsewhere. Spanish Modernism perfectly overlaps the Liberty aesthetics, which is not fascist. That came later.
Italian fascist art is better identified with rationalism, and fascist propaganda. Mussolini imposed some strict rules regarding it, like for example the inspiration by ancient Roman art, as ancient Rome's graandeur was what he wanted to recreate. Beside this, part of Italian fascist art were modernism (not in the Spanish sense), and avantgarde movements like Futurism and Rationalism, which all sustained fascist ideology. Quite the opposite of the free, rounded, natural forms, flowers, animals and decorations of the Art Nouveau.
Architecture was one of the fields where Italian fascist art was better expressed. You mentioned Asmara, but a similar town, called Latina was built from nothing after the reclamation of the swamps in the Pontino countryside. Or the EUR area in Rome, built to celebrate the 1942 Universal Expo.
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I can't imagine where you can see any resemblance to the Magical Modernist Mansion.