Inside the tunnels of Rome's ancient, extravagant Caracalla baths Rome’s Caracalla Baths epitomized the wealth of the ancient Roman Empire. Built to welcome up to 8,000 people a day, the ruins of the vast structure are one of the eternal city’s top tourist attractions. But now, the site’s vast underground tunnel system is also open to the public. Seth Doane got a look at the miles of Roman history being explored for the first time in centuries.