The largest carnival in Switzerland, and one of the largest in Europe, is the 'Basel Fasnacht'.
Basel Fasnacht lasts 3 days. It starts on the Monday 6 weeks before Easter Monday (the Monday after Shrove Tuesday and Ash Wednesday.)
There are also large 'Fasnacht' carnivals in Luzern and Bern.
Many other smaller towns and villages in north-west Switzerland have local Fasnachts. One of the most unique is the 'Chienbäse' in Liestal.