Bluebulb Projects' The Measure of Things presents:
660,000 is about ten times the number of Seats in The Colosseum.
In other words, the count of Seats in The Colosseum is 0.1 times that amount.
(a.k.a. The Coliseum, a.k.a. Flavian Amphitheatre, a.k.a. Amphitheatrum Flavium
, a.k.a. Anfiteatro Flavio or Colosseo
) (Rome) (estimated)