John McEnroe, Ivan Lendl, the Williams sisters and many other talented pros have built collections spanning Basquiat, Mucha, Warhol and beyond after leaving the tour behind.
In conversation with Observer, the artist's son discusses the genesis of "Rothko in Florence," a 15-year labor of love that places 73 works in dialogue with Fra Angelico, Michelangelo's library and three of the city's most storied spaces.