But the home of Mr. Cerruti’s collection, consisting of about 1,000 items from across the centuries, is the quirky Provençal-style villa he built in the 1960s, not far from the Castello, in the hills above Turin. Distinguished by its observation tower, which may have been inspired by the 10 Giorgio de Chirico paintings he owned — de Chirico had a major influence on the Surrealists — the house has been tactfully restored by the architects Baietto Battiato Bianco and Con3Studio and is now managed by the Castello. It officially opened to the public on Saturday; a minibus shuttles visitors from the Castello to the villa every hour.

“We’re in the era of collectors, and now we’ve collected a collector,” said Ms. Christov-Bakargiev, who was the artistic director of the 2012 Documenta festival of contemporary art before being appointed director of the Castello di Rivoli. She said she regarded Mr. Cerruti as a model of how wealthy individuals should acquire, enjoy and ultimately share their art. “He wanted his collection to become a public museum that was accessible to everyone,” she noted.