The magical barrier in J.K. Rowling’s Harry Potter books leads to Platform 9¾.
The platform is located at London’s King’s Cross railway station and is the departure point for the Hogwarts Express. Young witches and wizards reach it by walking through the barrier between platforms 9 and 10. Harry first learns how to find it when Molly Weasley helps him at the station.
The Hogwarts Express traditionally leaves on 1 September, carrying students to Hogwarts for the new school year. The platform therefore marks a recurring transition between ordinary London and the magical world.
Platform 9¾ is fictional, although King’s Cross has embraced the idea with a themed trolley installation and a shop for visitors. The fraction is not a real railway platform number. It is written with the fraction symbol three-quarters, making the exact form “9¾” part of the recognizable fictional location.