The Grotta di Seiano, located in Naples, is an ancient Roman tunnel carved into the tuff rock of Posillipo hill. Originally built to connect patrician villas with the ports of Puteoli and Cumae, it was rediscovered in 1841 and reopened as a tourist attraction in 2009. Visitors can explore this historic site, marvel at its architecture, and enjoy guided tours that offer a glimpse into the past. Don't miss out on this unique experience in Naples!