Wonderful place to visit in the Harz mountains. There is an optional paid tour but visiting the…read moreglass shop and Christmas shop is free. It's possible to see the glass being made in the glass shop. There are so many beautiful items made of glass to be seen. The marble area is also very fun. It's only 1€ for a small/medium marble and 2€ for a large marble. Seems to be very popular with the kids! Outside there is a huge playground. Highly recommended when visiting the Harz!