The Palazzo Grassi presents a major survey show of Youssef Nabil, “Once Upon a Dream.” Nabil’s artistic oeuvre—whether portraits, film, or landscapes—evokes a sense of romanticism, loss, and memory. It pays tribute to a time gone by, or one that maybe only ever existed in our dreams. While he’s collaborated with celebrities and actors like Salma Hayek, Catherine Deneuve, and Alicia Keys, his images remain deeply personal.