The Mannheimer Sommer is a free music festival that takes place every year in the city center. It features live performances from both local and international artists, as well as a vibrant atmosphere that is sure to get you dancing. The festival is a celebration of the city's music scene and culture, and is a great way to experience the local community. The festival takes place over a weekend in the summer, and is a must-visit for anyone looking for a fun and budget-friendly event in Mannheim.