More information about the event here.
I was downtown today for a different event and had a few minutes to visit "Lautern blüht auf," an event hosted by a business association. It's a way to welcome in spring with specials from the merchants, vendors of special goods in tents, and cultural presentations.
For example, the group below presented a cheerful dance routine.
Artisans and community groups set up tents to sell wares and raise awareness of various causes.
Downtown was completely chaotic today. In addition to the Latuern event, there was a soccer match, a political demonstration, and a counter-demonstration.