The Reichstags building only houses the debating chamber and the offices of the team that presides over the debates. All other activities take place in newer buildings in the vicinity of the 1894 iconic one. They are all connected by underground passages, one apparently wide enough for trucks to drive through. I’m not sure how big the trucks are that use them.
On our tour of the Reichstag we walked along one of these passages to the Paul Löbe Haus, built in 2002. The wide pillars you can see in the picture above are not just to provide internal support, but actually contain the root structures of trees above the passage way.
Although named after a distinguished parliamentarian of the Weimar Republic who was imprisoned in 1933 and returned to politics and served in the Bundestag, the building is often referred to by its purpose. It houses the 21 parliamentary committees. All have been allocated one of the round committee rooms and there are ancillary rooms associated with each one.
From that building you can also look out over the river Spree and see the parliamentary library, with its big circular window and a range of other blocks which house the press corps, offices of the MPs and other supporting services.
Another building, frequently shown as a backdrop is the one home to the Office of the Chancellor. It was built in 2001 and is opposite the main entrance to the Committee Building. Pictures for state visits are often taken in front of this building.