Fun things for children to do in Berlin?

[OldieMum]

We are going to Berlin for a few days next week. We are visiting DH's step-DD, who will, no doubt, have lots of ideas for things to see, but it would be great to get some suggestions for fun things to do with DD (4) and DS (8 months). Thanks.

bump

Bump. Anyone been to Berlin with children?

Yes, we went with ds last year when he was 3.5.
The Zoo is good and was right next to out hotel.
If you go to the Reichstag (impressive)entry is free but often long queues, however with a buggy you are allowed to queue jump and go in the diabled entrance with your own lift to the top.
We also went to the Olympic Stadium (not on a tour) which was good, nothing really for children but plenty of space for them to run around.

We live in Berlin but my 2 dc are abit older, so we've been to alot of the museums and that sort of thing.
Be prepared for an expensive few days though. For example Sea life is a huge aqaurium near Alexander Platz which attracts alot of tourists - always long lines of people waiting to get in but quite expensive. The zoo has a big attraction at the moment - the baby polar bear being presented to the public for the first time this weekend. In April a new indoor Legoland opens at Potsdamer platz, seemed to have alot on offer for smaller kids (pirate world etc) and if it pours down and stays nasty like at the moment there a quite a few indoor playgrounds around (try Jacks fun world) not cheap but worth it for an afternoon of fun for the kids.
If SSShakeTheChi is on here she knows loads more than I do - she's a Berlin expert!