Princess Peach's Castle/Second Floor

The second floor of Princess Peach's Castle is an area accessed in the later half of Super Mario 64. After collecting 31 stars and defeating Bowser in Bowser in the Fire Sea, Mario is able to use the key to access the second floor of the castle.

Geography
The second floor can be found past the double door that is found up the stairs in the main foyer. These doors lead to a spiral staircase that lead up to the second floor itself.

The second floor is a donut shaped room with blue sky-like walls. It has many paintings which cannot be entered, with the exception of a few: a painting of a Skeeter leading to Wet-Dry World, and a painting of Tall, Tall Mountain. There's a staircase in this floor that leads up to the third floor of the castle.

There is a door that leads to a triplet of identical paintings, all with different sizes. An example of perspective trickery has the room get progressively smaller or progressively larger approaching the smaller and larger paintings. This leads to Tiny-Huge Island.

Mirror Room
There is another door, surrounded with brown bricks, which leads into the infamous mirror room. This room is characterised by its large mirror which mirrors not only Mario but the Lakitu that is filming him. There are a series of paintings in the room, although there is a bland wall which appears as a painting of a snowman on the other side of the mirror. This empty wall leads to Snowman's Land.