No need to spend hours in a windowless museum to admire works of art. Along with New York and Detroit, San Francisco is one of the few American cities where tagging has been erected as an art form. The Mission District - the city's hippie neighborhood where Peace flags and portraits of Janis Joplin and Jimy Hendrix fly - is also home to some of the best graffiti artists on the West Coast. There are about 90 murals in very different styles in this neighbourhood. Most of them are located in the vicinity of the Precita Eyes Mural Arts and Visitors Center. Some of the graffiti is huge and covers three-storey buildings. They sometimes represent more than a week's work!