By Imogen Foulkes
BBC News, Berne
Switzerland is holding its biggest celebration of traditional Swiss culture - the famous Unspunnen Festival which takes place once every 12 years.
Who throws furthest wins - simple if you have the strength
It began originally in the early 19th Century as a way of uniting the country in the face of Napoleon.
For three days, there will be yodelling and alphorns, traditional dancing and alpine wrestling.
But the most important event is a competition to throw a stone that is revered as a national icon.
Stone-throwing does not sound a particularly suitable sport for the normally peaceful Swiss, but the 83kg (183lb) Unspunnen is no ordinary stone.
Britain has the Queen, France has its republic, Italy has Michelangelo's David and Switzerland has its stone.
The competition is straightforward. The stone must be lifted above the head and thrown. Whoever throws it furthest wins. Simple, as long as you can actually lift 83kg.
Surprisingly, in fact, the Unspunnen has been "lifted" all too often.
The original stone was stolen in 1984 by Francophone separatists campaigning to join the French-speaking region of Switzerland and to join the European Union - something the Swiss have resisted for years.
The festival is being held in the city of Interlaken
The stone was mysteriously returned in 2001. But to the horror of all those Swiss Euro-sceptics, the stars of the European Union had been carved into it, meaning the Unspunnen didn't even weigh 83kg any more.
Still, the beloved boulder was welcomed home with joy. Last year it was the prize exhibit in a show of folklore in one of Switzerland's top hotels.
Until, that is, it disappeared again. It was stolen for the second time from under the noses of its guards and a brick was left in its place.
So this year the stone-throwers will be lifting a copy of the old Unspunnen - minus the stars of course - but weighing exactly 83kg.