During the Italian Renaissance, Florence reigned supreme for its art and artists. And yet Siena stood unparalleled for its work in bronze, producing pieces of technical beauty that transcended the medium. Bronze turned up everywhere in the medieval hilltop city—in its churches and in its battlefields. Donatello sojourned there for five years. This exhibition at the Frick is the first to focus on the Tuscan city as a center of artistic excellence in the medium of bronze. It features 40 statues, reliefs, and objects, a majority of which have never left Italy—until now. —Maggie Turner