"Three up... two across he muttered. "Right, stand back, Harry."
He tapped the wall three times with the point of his umbrella.
The brick he had touched quivered -- it wriggled -- in the
middle, a small hole appeared -- it grew wider and wider -- a second
later they were facing an archway large enough even for Hagrid, an
archway onto a cobbled street that twisted and turned out of sight.
"Welcome," said Hagrid, "to Diagon Alley."