Endless stairs

The Endless Stairs is an obstacle within Princess Peach's Castle first appearing in Super Mario 64 and Super Mario 64 DS. It is behind the final Star Door, which leads to Bowser in the Sky. If the player has less than 70 Power Stars, they can still enter the Star Door, but they will endlessly climb this flight of stairs. If the player turns back after climbing the stairs for some time, its like they never went anywhere. Once the player manages to collect 70 Power Stars, the Endless Stairs finally ends.

Trivia

 * There is a glitch with which the player can bypass ever needing to collect at least 70 Power Stars, but only for the Nintendo 64 version.