The date is inspired by the date of the Federal Charter of 1291, Pacte du Rütli, placed in "early August", when "three Alpine cantons swore the oath of confederation" (Schwyz, Uri and Unterwald), an action which later came to be regarded as the founding of Switzerland.
I celebrated this holiday, doing a Mountain Bike tour, from Canton Schwyz to Canton Uri, over the Kinzigpass. This is a cluster of alpine farming huts. One of four I passed on my way.
You must be very fit Mona - cycling in Switzerland will require some strength and endurance skills. But what wonderful rich green scenery to view from your bicycle seat. It is a great sky too with the big clouds and you got the flag too for National Day.