Diagon Alley is a location in London, England on planet Hogwarts (Gamma Germanicus VII) that serves as the de facto center of wizarding society in Hogwarts' version of Great Britain.
Stores and other establishments are available in Diagon Alley that allow members of wizarding society to see to their various needs; among those businesses is the home branch of Gringotts Wizarding Bank, the chief financial services institution of the magical world.