Red Keep Stables
The Starks arrive at the Red Keep in episode 1x03 “Lord Snow”. A number of the Starks' attendants are murdered by the Lannister soldiers while unloading some cargo from which Arya later recovers her sword in episode 1x08 “The Pointy End”.
Red Keep Hallway
Ned is walking through the keep when a messanger informs him that the small council is meeting in episode 1x05 “The Wolf and the Lion”. Varys and Littlefinger inform Ned that the Goldcloaks are under his control in episode 1x07 “You Win or You Die”.