The event, known as Spancirfest (the Promenade Festival), will feature more than 1,000 participants from 16 countries who will give some 150 performances in the town's streets and squares.
Performing will be acrobats, conjurers, jugglers, clowns, stilt walkers, actors, musicians and traditional artisans.
Organisers have said that all performances will be free thanks to financial support from more than 60 sponsors, which will cover nearly 80 per cent of the budget of the event.
The festival is expected to draw between 120,000 and 130,000 visitors.