Post-Versailles Europe saw the emergence of new, quasi-state territorial corporations (enjoying a great deal of autonomy, but not sovereignty). These included the Free State of Fiume/Rijeka (1919- 1924), Free City of Danzig/Gdańsk (1920-1939), Free State of Memel/ Klaipeda (which emerged between 1920 and 1923, before being incorporated into Lithuania with partial autonomy still remaining), as well as, slightly later, the autonomous Åland Islands (1922), and the Republic of Hatay (1938-1939). In theory, those international law constructs were supposed to resolve tensions (including those erupting on the grounds of nationality) between neighbours vying for control over strategic territories (and cities). However, they proved to primarily spark new conflicts of varying length. The article constitutes an attempt at comparing the geneses and development of the first three of the abovementioned “free cities”, as well as identifying their role in the newly-formed League of Nations. In addition, the article attempts to determine the degree to which the principle of national self-determination played a role in the establishment of these entities, as well as the methods used to ensure that the national minorities which found themselves within the borders of these “free cities” were protected.