 It may more specifically allude to features drawn from the funerary catafalque and thus appropriate to Saint Peter, and from the traditional cloth canopy known as a baldacchino that was carried above the head of the pope on Holy Days and therefore related to the reigning pope as the successor of Saint Peter.The idea of the baldachin to mark Saint Peter's tomb was not Bernini's idea and there had been various columnar structures erected earlier.The old basilica had a screen in front of the altar, supported by 2nd century Solomonic columns that had been brought "from Greece" by Constantine I (and which are indeed of Greek marble).