Claes Oldenberg, the artist who made the giant steel clothespin sculpture in Philadelphia's Centre Square, has died at 93 years old. The Swedish-born artist was an influential figure in the development of pop art and become widely known for his public commissions in cities around the United States and the world. Oldenberg's other works in Philadelphia include "Split Button," a sculpture installed in 1981 at the University of Pennsylvania's Blanche Levy Park, and the "Giant Three-Way Plug" sculpture outside the Philadelphia Museum of Art.