Inside Basilica of St. Francesca Romana there is a vulcanic stone sheet where you can see the marks of St. Pietro's knees. The legend has it that a swindler magician called Simon Mago was in Rome and Emperor Nero was curious about what he heard about him. He also heard stories about the Apostles so he decided to call the magician and the Apostles to see their marvels. A competition was organised and a crowd gathered to watch the performances. Simon Mago started to fly up to the sky in front of the Emperor; Apostles Pietro and Paolo knelt down and prayed for his falling. He eventually fell on the ground and died.