The Colosseum

[The Librarian]

A quote reads: “as long as the Colosseum stands, so shall Rome; when the Colosseum falls, Rome shall fall; when Rome falls, so falls the world.” However, the Colosseum was not the arena in Rome, as other answers have pointed out - it was the name of a colossal statue of Nero known as the Colossus of Nero; the arena was called the Flavian Amphitheatre.