Palmengarten, a park here in Frankfurt, Germany. The exhibition is called "Winter Lights". Last year I was there for the first time with a friend and we both were impressed. I have shared photos of that exhibition in my blog here. This year we decided to visit the park again and it was amazing. All the colorful illuminations of trees and buildings are so beautiful and the other exhibition items were interesting as well. We spent about 2 hours there in the dark and although it was quite cold it was so much fun.