The same thing happened with the first two Potter flicks. Filming took place in different places around the country, including Alnwick Castle in Northumberland.
Fans flocked to have their photos taken where Ron and Harry stood in the films.
And what that meant was the hotels and shops in those areas also had loads more visitors.
Highlander magic
Bits of Braveheart were filmed in Glencoe
But Glencoe is no stranger to big Hollywood stars setting up home in their towns.
The scenery of Glencoe is extremely dramatic and ghostly. It's full of history and has been used in films for over 30 years.
Braveheart, Rob Roy and Highlander have all been filmed there.
The release date for Harry Potter and the Prisoner of Azkaban hasn't been decided on, but it's thought it will hit our screens sometime in 2004.
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Watching filming at Leavesden
