In Germany alternative energy sources area is growing extremely fast and people who uses it have even some bonuses from government. There are too many solar panels and windmills. You can even install solar panels at the roof of your house and sell it (in the same time you still can buy). Interesting moment here is that you can sell it with higher rates than buy from the city. It makes the deal profitable =)
There is even a mosque in Bremen which is quite beautiful.
Another attraction around is Christmas shop where you can buy some stuff the whole year round, not just a couple of days before the actual Christmas. Nearby there is a huge building where curious (and not really curious) children can watch physics experiments and other scientific achievements.
Probably that was the main points of interest in this city (: