The Reichstag is the seat of the German federal government. In the 1990s, Sir Norman Foster did a reconstruction and extension project for the building, adding a dome and renovating the interiors. The building is open to the public. However, with only 1 elevator to the dome, there was about a 30 minute wait outside on a sunny afternoon.
The dome features a huge column in the middle with a ramp going to the top along the edges. Unfortunately, it was very hard to take pictures due to the angle of the glass and the glare.
There is an open deck just outside the dome that offers a panoramic view of the city. However, it is not high enough to give a very good vantage point. But then, I have been up a number of viewpoints in both the west and east already.