Cheap/Free Things to Do around Hannover

This is another email from my friend Ben, which is worth sharing for anyone else who might end up in Hannover. (Thanks again Ben! Assuming my visa hurries along a bit I should be there next week!)

"I was thinking when you get here, you'll want to do/see interesting stuff, but will probably be fairly poor for the first few months getting set up and so on.  So, I made a list of free or cheap stuff to do in/around Hannover:

- Hannover Old City:
Really just means wandering around the town a bit - good for a single day one weekend though.  We can head up the tower on the "new" town hall; stop at random cafes for coffee or beer; etc.

- Castle Marienburg:
Our "local castle" for Hannover.  Kind of a girly palace-y kind of castle and not as impressive as some of the more famous ones (which are all a bit further away), but pretty cool in general. 

- Wilhelmstein Fortress:
A fortress on a man-made island in a lake just a few km west of Hannover.
3 euro to take the boat across the lake to get there (and back).
There's a restaurant on the island as well, so would be good for a "lunch trip".
I haven't been there yet.
http://www.wilhelmstein.de/

- Lüneburg:
A small city between Hannover and Hamburg (closer to Hamburg).  Didn't get bombed at all during WW2, so has lots of cool old buildings and original street layout.
I've been there a few times and can recommend places to drink coffee etc.

- Hamlen:
As in, the "Pied Piper" town.  It's just south of here and has a pretty nice old city area.

- Various natureparks etc:
Steffi insisted I add this suggestion.  It wouldn't be my recommendation in general, but you might enjoy it.
(Abigail's note: I actually do really enjoy parks/gardens, so this is excellent!)

- Beergardens:
Simply sitting around in a beergarden on a summer's day can be quite nice.  Given the cost of a half-litre is around 3 euro at most of them; if you drink slowly you can waste a good few hours without
seriously spending any money.

- Others:
Take a look at http://www.tourismusregion-hannover.de/Start_en.bspx various touristy things in this region.