Schloss Charlottenburg was the Berlin "palace" retreat of Sophia-Charlotte, wife of King Frederick I and grandmother of Frederick the Great. She's famous for having interests in philosophy, science and music and her friendship and correspondence with Leibniz, who tutored her mother. The grounds started out modest, but were built up into an opulent baroque palace after Frederick became King -- here's an HDR of a corner of one of the Rococo rooms, showing a ceiling painting and ornamentation. Sophia-Charlotte's monogram was placed by Frederick I when he decorated this room after her death.
There was a separate USD $5 charge for permission to take photos inside, which is an interesting idea. It's certainly preferable to the standard "no photography allowed" of modern exhibits. I think they also tried to make claims about what the photos could be used for afterwards, though.