free city

plural free cities

1. historicalAny of various types of city of Europe from classical to modern times, characterised by relative autonomy and/or being responsible only and directly to a king or emperor; a more modern city of such type, sometimes elsewhere than in Europe.

   1727, Nathaniel Lardner, Credibility of the Gospel History, 1815, The Works of Nathaniel Lardner, D.D., Volume 1, Thomas Hamilton, page 124, Pliny calls ᵉ Tarsus a free city: which is an incontestable proof it was not a Roman colony, for then he would have called it so.

   2 more examples

   1835, Free Cities, article in Francis Lieber, Edward Wigglesworth, T. G. Bradford (editors), Encyclopædia Americana, Volume 5, New Edition, page 311, The remnants of this league, with the former confederacy of cities, which had its representatives in the German diet, and the free cities of Hamburg, Bremen and Lubeck, were incorporated with the French empire in 1810. As these cities coöperated vigorously in the recovery of German independence, they were acknowledged, together with Frankfort, as free cities, by the congress of Vienna. […] Besides these four free cities in Germany, Cracow (q. v.) was likewise declared a free city by the general act of the congress of Vienna, and is under the protection of Russia, Austria and Prussia.

   The High Commissioner of the Free City of Danzig was a position established under the Peace Treaty of Versailles that concluded World War I.

   2009, Matthew Parish, A Free City in the Balkans: Reconstructing a Divided Society in Bosnia, I.B. Tauris, page 210

2. A special economic zone.