Geneva
Geneva celebrates Jeune genevois on the first Thursday following a Sunday in September.  By local tradition, this commemorates when the news of the St. Bartholomew's Day massacre of Huguenots reached Geneva.  The Genevois (people of Geneva) joke that the federal equivalent holiday, Jeune fédéral, is celebrated two weeks later on account of the rest of the country being a bit slow on the uptake.