Frank Stella turns 71 this spring, and his latest work—a series of mammoth sculptures, some of which will need to be delivered by flatbed truck—demonstrates that he is more fearless than ever. Not that he'll tell you this himself. Stella is a wised-up, unsentimental type, with a Massachusetts accent gone New York. Gripping an unlit cigar and wearing a red baseball cap, he's seated at a marble desk on the second floor of his Chelsea gallery, Paul Kasmin, talking about plans for three upcoming shows. Stella could pass for your impatient uncle, frequently beginning his sentences with "Look" or "Listen." It sounds as if he wants to set you straight before you embarrass yourself.

At an age when some artists would be thinking about how to make things smaller and easier for themselves, Stella has exploded the size and difficulty of his work. It means he has to drive an hour and a half from his comfortable West Village home—a loft building he's owned since 1967—up to a 30,000-square-foot studio near Newburgh, New York, several days a week. There he executes the Brobdingnagian sculptures that take a team of 10 to produce. "Look, I'm addicted," he says. "I can't help it."

The gray hair shouldn't fool anyone. Stella is a wiry five foot seven and moves quickly. At one point he has to get up and nervously circle the room. As he explains some of the engineering involved in the new work, he compulsively grabs at his right arm with his left hand, which is missing part of a finger from a childhood accident. This is an artist who itches to stop talking and start working.

Stella's not the only one making art on such a grand scale—Richard Serra's grave spiraling walls are taking over the Museum of Modern Art in June—but as he says, "It just comes out slightly more intense when I do it." That's an understatement from a man who has never lacked ambition or recognition. Stella was instantly canonized for his Minimalist canvases of the fifties and sixties, and then, unlike so many artists, refused to repeat himself. Not everyone appreciated what followed, but Stella didn't really care. He quotes an old friend, the dealer Sidney Janis, on how to look at reviews: "He used to say he didn't read any art criticism, he only measured it."

Now more fodder for critics and fans is on the way with two concurrent shows at the Metropolitan Museum of Art: "Frank Stella on the Roof" and "Frank Stella: Painting into Architecture." In addition to a decades-spanning selection of smaller models and drawings down in the galleries, the roof will include his recent 17-foot-tall adjoeman, a 3,100-pound stainless steel and carbon fiber sculpture whose flat black sheet and silver tubing could be a Russian Constructivist design for a ship's mast, and a new work about the size of a pile of 16 Humvees called Chinese Pavilion. (Though some of these bear Indonesian names he came across on a trip to Bali, he frequently borrows the titles for his pieces from Scarlatti keyboard sonatas—not because he's a musicologist; he just figures that with over 500 of them to work through, he'll never run out.)