From the beginning of the 19th century to the 1950s the method of city planning changed drastically. In my thesis I inspect urban utopias and their impact on reality through the analysis of three Hungarian socialist city plans. Two "new cities": Dunaújváros and Salgótarján. And a housing estate in Budapest, Újpalota. My aim is to see the architectural and sociological impacts the utopias left on the world and specifically on Hungary before the change of regime.