The bronze and gilded baldachin was the first of Bernini's works to combine sculpture and architecture and represents an important development in Baroque church interior design and furnishing. The canopy rests upon four helical columns each of which stands on a high marble plinth. The columns support a cornice which curves inwards in the middle of each side. Above this, four twice-life-size angels stand at the corners behind whom four large volutes rise up to a second smaller cornice which in turn supports the gilded cross on a sphere, a symbol of the world redeemed by Christianity.