In J. K. Rowling's Harry Potter novels and their filmed adaptations, Diagon Alley is a fictional alleyway in London accessible to witches and wizards but invisible to Muggles, containing numerous shops selling magical supplies. These include Flourish & Blott's (a bookstore), Ollivander's (makers of magic wands since 382 BC) and Eeylops' Owl Emporium. The Alley is also home to The Leaky Cauldron Inn, and Gringotts Bank, which is run by goblins.
In the film Harry Potter and the Philosopher's (aka Sorcerer's) Stone (2001), Diagon Alley appears to be a short walk away from Leadenhall Market in the City of London.
The name seems a possible pun on "diagonally"; evidence for that can be found in the movie version of Harry Potter and the Chamber of Secrets (2002). The DVD of that movie includes a video "guided tour" of Diagon Alley, apparently shot on the original movie sets.
Leading off of Diagon Alley is the dark and dingy Knockturn Alley.
