1. Rowena Ravenclaw came up with the idea for this
2. leads Harry, Ron Weasley, and Hermione to the out-of-bounds third-floor corridor
3. You can get a great view of all the paintings!

when Harry Potter first learns about the moving staircases, is quite breathtaking. A moving staircase in Philosopher’s Stone is what leads Harry, Ron Weasley, and Hermione Granger to the out-of-bounds third-floor corridor and their first encounter with Fluffy, the three-headed canine guardian of the Philosopher’s Stone. (All information taken from Pottermore)