A hitherto unrecorded variant of the picture of 1751 in the Harrach Collection, Vienna (F. Arisi, Gian Paolo Panini e i fasti della Roma del '700, Rome, 1986, p. 441, no. 424, illustrated); in that picture, which is of similar size, the Arch of Constantine is shown in place of the Arch of Janus and the soldier to the left of the philosopher is in a different pose