" Welcome, " said Hagrid, " to Diagon Alley." He grinned at Harry's amazement. They stepped through the archway. Harry looked quickly over his shoulder and saw the archway shrink instantly back into solid wall.
A sign overhead said Hogwarts Express, eleven O'clock. Harry looked behind him and saw a wrought-iron archway where the barrier had been, with the words Platform Nine and Three-Quarters on it, He had done it.