Warner Bros. bought the film rights to the book in 1999 for a reported £1 million ($1.65 million). Production began in the United Kingdom in 2000, with Chris Columbus being chosen to create the film from a shortlist of directors that included Steven Spielberg and Rob Reiner. Rowling insisted that the entire cast be British, with the three leads chosen in August 2000 following open casting calls. The film was shot at Leavesden Film Studios and historic buildings around the United Kingdom, from September 2000 to March 2001.