may 23: the »Grundgesetz« (intended as a provisional constitution) of the Federal Republic of Germany applies (1949)
In 2024, this anniversary is celebrated in Kiel, among other places.

Party in Kiel zum 75. Jahrestag des Inkrafttretens des Grundgesetzes der Bundesrepunblik Deutschland
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Party in Kiel to mark the 75th anniversary of the entry into force of the Basic Law of the Federal Republic of Germany