Bundestag

Actually the building is called "Reichstag", Bundestag being the institution using the building, the German parliament.

It's here, where you probably can find the longest queues in Berlin. Especially in Summer, people are queueing up for hundreds of meters. They all want to visit the huge glass cupola that was erected on the roof. The dome is open to anyone without prior registration and allowes for a fantastic view over Berlin.

Waiting in the queue can be very funny as Berlin's street artists know where to find their audience.

The huge lawn in front of the Reichstag building was used as a soccer field by Berlin's youngsters until this was prohibited. Now they play long-distance frisbee, so be aware of flying objects.

Historic details about Reichstag: Wikipedia