Burns' Surveillance Room first appears in Burns' Heir.
Charles Montgomery Burns shows Bart the room and it's capabilities. It is a room full of televisions showing footage from secret cameras throughout Springfield. This is how Bart finds out Homer is eating flowers. Also, Mr. Burns uses this room to stage 742 Evergreen Terrace's family, where the actors said they no longer missed Bart. This was so Bart would stay at the mansion.