Bernini designed two elegant marble "cantorie" for the instruments which are supported by stucco angels and putti displaying rich garlands of flowers and the coats of arms of Pope Alexander VII. These organ lofts are display cases of the Chigi-Della Rovere dynastic symbols: the central newel post of the balustrade is decorated with the carving of an oak tree, the ancient symbol of the Della Rovere family, while the side pillars bear the mountain and the star symbol of the Chigis which reappear among the gilt wood carvings of the handrail among leafy oak branches. On the remaining organ-case the pipes are carried by four spreading, gnarled branches of a gilt oak tree complete with leaves and acorns.