To usher in the summer music festival season, we take you to a pastoral hillside in the Swiss Alps for the International Alphorn Festival held each summer near the town of Nendaz. Musicians are gathering here this weekend to celebrate and blow these enormous traditional horns of the Alps. No one really knows the origin of the alphorn. We do know that for centuries, European mountain folks from the Alps and east to the Carpathian Mountains used this horn to signal to each other across great distances and to call in animal herds. Even though the horn has no valves or keyholes, it’s not easy to play and requires great lung power.