Peel back the layers of Roman history—quite literally—with a thrilling exploration of its underground tombs and chapels. Visit the Catacombs of Santa Priscilla, home to stunning frescoes and thousands of centuries-old bones, including those of two Catholic popes. Learn about early Christianity from your guide while meandering the endless darkened tunnels. Next up is the Capuchin Crypt, where you'll find the artistically displayed bones of 4,000 Capuchin monks. Finally pay a visit to Nicola in Carcere and be surprised of how many layers this incredible "lasagne church" has.