I met my friend Eric in Copenhagen to help him clean out a storage shed. It was leftover from his Masters in Industrial Design, and full of really interesting artifacts of his courses. In between a few sessions at the storage shed we walked around the city and he showed me parts I hadn't seen, including Nyhavn and Christiania.
One really fun thing we found was an art installation near the infamous new biking bridge. It was an inconspicuous dome with a sign only asking that you wait for any people inside to exit, and you remove your shoes before entering.
The inside was delightful! The floor is solid mirror and so are many of the panels, giving it an infinite reflection when you look in many directions. Anything that isn't mirror was dyed plexiglass. We got lucky and walked by when no one else was around, so we stayed inside for a good 10 minutes.