The look of St. Paul's outside the walls before the fire of 1823
More than 130 m long, over 60 m wide and featuring five naves, the Basilica of Saint Paul was the biggest Roman basilica built under Constantine. It retained this layout until its reconstruction in the nineteenth century, after it was destroyed by fire in 1823.
Giovanni Battista Piranesi, Veduta della basilica di San Paolo fuor delle mura,in: Id., Vedute di Roma disegnate ed incise da Giambattista Piranesi Architetto veneziano, vol. I, Paris 1836