I remember seeing this in Star Wars, but can't remember its name or location. It was a large, tall, silver, circular room. There were many balconies facing inwards towards the center, where Palpatine stood on a platform. In each balcony sat two people, who appeared to be diplomats. Any ideas? :)

The Grand Convocation Chamber, also referred to as the Senate Rotunda, Senate Arena, Senate Chamber, Great Rotunda, was the largest room in the Senate Building, in the Senate District on Coruscant and the heart of the Galactic Senate.

Grand Convocation Chamber - Wookieepedia, the Star Wars Wiki