Moaning Myrtle's bathroom (out of order)
Harry tore up the stone steps, through the oak front doors, and off up the marble staircase, toward the second floor.This presented a question of how Dumbledore that year could have wound up in the Room of Requirement early in the morning when in urgent need of a bathroom, since the Room of Requirement was on the seventh floor in Harry's fifth and sixth years. In book 6 the entrance to the Headmaster's office was relocated to the seventh floor.
Five minutes later he was hurtling toward a stone gargoyle standing halfway along an empty corridor (GF28)
suit of armour
The office changes hands every year, so the decor is different every time.
- Quirrell - unknown 1991-1992
- Lockhart - vanity pictures of himself 1992-1993
- Lupin - grindylow tank and other creatures for use in class, tea things 1993-1994
- Moody - Foe-Glass, Dark Detectors, seven-lock chest 1994-5
- Umbridge - plates on the wall with foul kittens in bright colors, frilly doilies and the like, flowered tablecloth 1995-6
"Saturday afternoon seemed to melt away, and in what seemed like no time, it was five minutes to eight, and Harry was dragging his feet along the second-floor corridor to Lockhart's office. He gritted his teeth and knocked." (CS6)
Possible plan of the second floor
This map of the second floor of the castle takes the details from the books into account as well as the standard structure and architecture of castles. While not canon, this map is probably as close to the "real thing" as we're ever going to get.