Last year on my visit to Hamburg I visited an amazing museum, the most unusual museum I've ever seen. MINIATUR WUNDERLAND HAMBURG is the largest model railway in the world with 20 km of railtracks, 1300 trains and 500.000 lights.
If you ever come to Northern Germany, you don't want to skip this place. But if you come it may take all your time, because you would not want to leave. Here's an amazing promo video of the museum and my travel photos from Hamburg.