This amazing construction sits inside the glass dome atop the Reichstag building and directs virtually all the sunlight hitting the dome down into the parliamentary chamber. I reckon they stole the idea from James Bond - I'm sure Moonraker had something similar...
This is a very impressive building - the exterior is a dramatic zinc clad zig zag, criss-crossed with jagged slashes; the interior is divided into several axes each with a theme and each broken up by dramatic open spaces (the architect calls them "voided voids").
While swathes of Berlin feature beautiful, uber-modern new buildings popping up like mushrooms, there are still plenty of examples of communist-era buildings...