The studio sits 3 miles north of central Watford in the village of Leavesden, in a complex built for assembling Halifax bombers during the Second World War and converted to film production in the 1990s. The "Making of Harry Potter" tour opened in 2012 and has run continuously since, with new additions (the Forbidden Forest, Platform 9¾, Gringotts) added every few years.
The visit takes three to four hours. Highlights are the Great Hall, the full-scale Diagon Alley exterior, the 1:24 scale model of Hogwarts Castle (used for wide shots in the films), and the costume and creature workshop. Booking is essential — tickets sell out weeks in advance and there are no walk-ups. A shuttle bus runs from Watford Junction station on weekdays.