In December 2000, the Spanish artist Santiago Sierra paid four people to have a line tattooed on their backs. As Sierra explained it: “Four prostitute(...)

Deliberately provocative? A Catholic church that has been transformed into a mosque for the Venice Biennale by artist Christoph Buchel. Photograph: Casey Kelbaugh/The New York Times

Pickled sheep; blocks of turf; sculptures made from human blood: art can be many things. At this year’s Venice Biennale, Swiss artist Christoph(...)