Bluebulb Projects' The Measure of Things presents:
530,000 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)
Built between 70 and 80 AD, The Colosseum was a central attraction of Rome, capable of seating 50,000 spectators for various events including plays, war reenactments, and gladiatorial matches. The structure was estimated to require 100,000 cu. m of stone to construct. It remains the largest amphitheater in the world.