Yes at Zeil . There are so many shops where you can buy lots of unbranded things . Go to Zeil galleriea. Kauffhoff, C&A etc. Zeil is full of every type and budget of shops. Just go and explore the area.
We both really enjoyed the Film museum. Particularly of interest to anyone who is keen to know about the technologies developed in the lead up to being able to make films and lots of hands on interactions
On Christmas Eve everyone gathers in the main platz with friends, family, dogs, snacks, champagne, and gluhwein and waits for the 4 churches to ring their bells at the same time at 5 o'clock. It was a cool tradition to be a part of.