Whether casting sculptures from human excrement or paying junkie prostitutes to have a line tattooed on their backs, Spanish artist Santiago Sierra is a provocateur whose art raise headlines.
We filmed his latest performance piece at Tate Modern and asked him about this and other controversial works. Contains some strong language.
Find out more about Santiago Sierra: https://goo.gl/xapyux
More info: http://www.tate.org.uk/art/artworks/sierra-160-cm-line-tattooed-on-4-people-el-gallo-arte-contemporaneo-salamanca-spain-t11852
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