The world's first ' Immaterial' sculpture sold for $17,000 (€15,000) in Europe. Italian artist Salvatore Garau sold an invisible sculpture for $17,000 providing the buyer with a certificate of authenticity to confirm its existence. (2021)

The 67-year-old artist Salvatore Garau sold an "immaterial sculpture" - which is to say that it doesn't exist. The 'lucky' buyer went home with a certificate of authenticity and a set of instructions: the work, per Garau, must be exhibited in a private house in a roughly five-by-five-foot space free of obstruction.