^The slightly higher estimate for seating numbers, and the lower estimate for arena length are in Richardson, L., A new topographical dictionary of ancient Rome, The Johns Hopkins University Press, 1992. pp. 366 - 7, showing reconstructed ground plan: convenience link
^Humphrey, John H., Roman Circuses: Arenas for Chariot Racing, University of California Press, 1986, p.3: link Humphrey gives a seating capacity estimate of 150,000 for the Circus Maximus.
^Cassius Dio, Roman History, (epitome), 78, 25.2: link This ruinous Collosseum fire was caused by lightning – one of many divine signs to anticipate the death of the emperor Macrinus.