Narni’s main drawcard is this extraordinary subterranean underworld. Discovered by a group of young speleologists in 1977, and originally accessed through an opening in a hillside vegetable garden, it unravels like something out of a Dan Brown novel. Tours take in a 13th-century Benedictine church, covered head to toe in frescoes; a Roman cistern; ancient aqueducts; and, most chillingly, an Inquisition courtroom and jail cell, covered in prisoner graffiti.
Roerto Nini, one of the six cavers who discovered the site, still leads some tours, which are in Italian, though audioguides are available in English, French and German, and written guides in several other languages. He has spent a lifetime studying his finds and tells how his research has taken him from the Vatican archives to Trinity College in Dublin.
The hour-long tour ends in the deconsecrated 12th-century San Domenico church, which is normally closed to the public outside of special events and concerts.
Guided tours run at noon and 4pm weekdays; at noon, 3pm, 4.15pm and 5.30pm on Saturdays; and at 10am, 11.15am, 12.30pm, 3pm, 4.15pm and 5.30pm on Sundays from mid-June to mid-September. During the rest of the year visits are limited to weekends. Check the website for details.