Sang a Klang
Parking is scarce so you might want to come with public transport (bus #19) or walk down from the city center or the Rives de Clausen(about 10min).
There is also the new elevator going down from Parc Pescatore to Pfaffenthal - from there is is just about 300m to the Sang&Klang:
Please note that all tickets at the box office must be paid in cash! In the days before the concert you can buy tickets at the CD Buttek am Palais (directly opposite of the Grand Ducal Palace in Luxembourg city).