Sounds like a a crazy story: Rome’s Colosseum to get $12M high-tech retractable floor.     https://nypost.com/2020/12/23/romes-colosseum-to-get-12m-high-tech-retractable-floor/     Summary: I'm not sure the reason for a retractable floor other than to use the Colosseum as a modern concert venue.   guy also known as gaius