The Reichstag building, the house Parliament in Berlin and another architectural beauty. The main attraction in this building is the Glass dome, which gives a 360 degree aerial view of Berlin city. But, one small hitch.. you need to book your visit to the glass dome at least a week in advance. It is a well secured building, and the booking to visit here can be done online, or at the office there. We were not aware of this, and so we missed the chance to go up to the dome. So, do your research well if you want to visit this building (not just from the outside :P).