At 96, the American-born, Italy-based sculptor Beverly Pepper has spent six decades bending metal to her will and rewriting the rules of modern art. IT’S EARLY ONE APRIL morning in Todi, Italy, and the installation is already underway: the four sculptures in pieces on a flatbed truck in the deserted piazza; the dawn sky lit a dramatic ombré, like a Giorgio de Chirico painting. Within the hour, the town begins to wake: flocks of schoolchildren, men and women oblivious to the russet-colored steel monoliths — each around 33 feet high and weighing about eight tons — slowly rising in their midst. The artist arrives, observing the scene from a small white car tucked in a corner of the piazza. “I get goose pimples,” she says. “It’s been 40 years.” It’s hard to imagine now, but in 1979, when the American sculptor and environmental artist Beverly Pepper first created the columns for this ancient Umbrian hill town, their presence was controversial. Monumental contemporary sculpture was novel here then, and Todi’s modest square, which dates at least to the 11th century, is itself a sacred space: The evening I arrived, I was met by the face of Christ, his blurry visage projected on the duom...