Which European country was reunified in 1990?

The German reunification was the process in 1990 in which the German Democratic Republic (East Germany) became part of the Federal Republic of Germany (West Germany) to form the reunited nation of Germany, and when Berlin reunited into a single city, as provided by its then Grundgesetz constitution Article 23. The end of the unification process is officially referred to as German unity, celebrated on 3 October (German Unity Day). Following German reunification, Berlin was once again designated as the capital of united Germany.

The East German government started to falter in May 1989, when the removal of Hungary's border fence with Austria opened a hole in the Iron Curtain. It caused an exodus of thousands of East Germans fleeing to West Germany and Austria via Hungary. The Peaceful Revolution, a series of protests by East Germans, led to the GDR's first free elections on 18 March 1990, and to the negotiations between the GDR and FRG that culminated in a Unification Treaty. Other negotiations between the GDR and FRG and the four occupying powers produced the so-called "Two Plus Four Treaty" (Treaty on the Final Settlement with Respect to Germany) granting full sovereignty to a unified German state, whose two parts were previously bound by a number of limitations stemming from their post-World War II status as occupied regions.