In 1999, Rowling sold the film rights of the first four Harry Potter books to Warner Bros. for a reported £1 million ($1,982,900).[66] Rowling demanded that the principal cast be kept strictly British but allowed for the casting of Irish actors such as the late Richard Harris as Dumbledore and of foreign actors as characters of the same nationalities in later books.[67] After extensive casting,[68] filming began in September 2000 at Leavesden Film Studios and in London, with production ending in July 2001.[69] Harry Potter and the Philosopher's Stone was released in London on 14 November 2001.[70][71] Reviewers' comments were positive, as reflected by an 80% Fresh rating on Rotten Tomatoes[72] and by a score of 64% at Metacritic, representing "generally favourable reviews".[73]