Maurizio Cattelan is known for his irreverence. Author of “The Single Post Instagram” and the man behind the taped banana that famously sold for $120,000 at Miami Art Basel, he is one of the world’s most controversial artists. In 2011, at the 54th Venice Biennale, he arranged 2,000 taxidermy pigeons near the ceiling of the Italian pavilion. In 2016, he replaced a public toilet at the Guggenheim with a fully-functional replica in 18-karat gold, available for use and cheekily titled America. For his first solo exhibition in Milan since 2010, Cattelan tackles existential themes of fragility, memory, and loss in a site-specific installation. —E.C.