Every year on May 5 (Liberation Day), there is a free open-air concert on floats on the river Amstel, near theater Carré.
It usually starts at 9pm, and if you would like to see something, it is advisable to come on time.
The concert is traditionally attended by the King and Queen. They arrive by boat, and also leave by boat. When they leave, traditionally the song 'We'll meet again' of Vera Lynn is played.
Around May 4 and 5 there are many more activities, described in detail on the website (but unfortunately only in Dutch).
Liberation Day concert on river Amstel (May 5)