What was one of the unique architectural features of the Colosseum?
A It had a retractable roof.
B It was a free-standing structure.
C It was built into a hillside.
Fact: Unlike many earlier amphitheatres, the Colosseum was an entirely free-standing structure, demonstrating advanced engineering with its use of arches and vaults that allowed it to support large crowds.
Correct Answer: It was a free-standing structure.