Ascona Festival, Various venues, Ascona, Switzerland

For much of the year, nothing much happens in the Italian-Swiss hamlet of Ascona. The town sits there, looking ludicrously pretty, with its Renaissance bell towers and ochre monastery reflected in the waters of Lake Maggiore.

For much of the year, nothing much happens in the Italian-Swiss hamlet of Ascona. The town sits there, looking ludicrously pretty, with its Renaissance bell towers and ochre monastery reflected in the waters of Lake Maggiore.

But in the past week, it has seen an invasion of about 300 musicians, all engaged in the much-maligned art of traditional (or classical) jazz. This annual alfresco event has evolved over 19 years from a gathering of local jazz fans into the biggest mainstream festival in Europe. Six stages line an idyllic waterfront, as bands play through the long, warm nights. The cumulative effect is like a traditional-jazz Glastonbury, and this year it attracted close to 100,000 cognoscenti.

Where else would you see Marty Grosz, the 73-year-old guitarist and jazz folklorist, playing Irving Berlin and Fred Astaire standards beneath a 14th-century church tower?

And where else would you see New Orleans jazz and Mississippi blues performed as they should be, rather than as mouldy cabaret, far removed from the original, revolutionary sounds of King Oliver and Louis Armstrong? In Ascona, two young New Orleans musicians pointed to a brighter future for trad jazz. Leroy Jones's warm, brawling horn, leading a tight quintet, reclaimed Dixieland with a new, inventive angle, while clarinettist Evan Christopher, sitting alongside the 90-year-old saxophonist Franz Jackson in Lars Edegran's impressive ensemble, powered through supple, high-velocity solos which blew the ancient standards into a new era.

But the main focus at Ascona was the first of this year's centenary tributes to Bix Beiderbecke, the white college boy from Iowa who ran away to play jazz cornet, lived very fast and died very young.

Beiderbecke was the first white musician to influence the path of jazz and, pre-empting the nearby Locarno Film Festival's prestigious "Jazz and the Cinema" retrospective in August, the centrepiece of Ascona was a concert reuniting the musicians who performed the soundtrack to Bix, the Italian director Pupi Avati's 1991 film.

Above all, Ascona reconnects the European Diaspora to the great African-American art form, and this unique ensemble ranged from the American saxophonist and soundtrack arranger Bob Wilber to the veteran Italian guitarist Lino Patruno, who co-scripted the film.

A storm crashed over Lake Maggiore as the band launched into a collection of Beiderbecke classics, with Avati's film playing silently as a backdrop. Despite the conditions, the capacity audience stayed to hear a dazzling, two-hour homage, which somehow sailed over a force 10 gale and glided to a close, just as the credits rolled and the thunder faded.