In the location's words:

The open air festival at the TV tower.
This summer, the 45Hertz Open Air Festival will take place for the fifth time in a relaxed atmosphere at the foot of the TV tower on the square at the Hamburg Messe West entrance: 17 days, 17 events, up to 20,000 visitors.
The festival blends harmoniously into the Karoviertel district and follows three clear values: tolerance, diversity and cultural variety. The 45Hertz Festival stands for itself: Focus on artists and creators in the middle of the city and in the middle of summer.