Trail dei Papi – Discovering Lazio. Trail Dei Papi is a 600-kilometer cycling route that few know about. The trail takes place via secondary and dirt roads, passing picturesque villages, historic villas, unforgettable views, and places that seem to have been lifted from a novel from many years ago. The Trail dei Papi isn't just a gravel route; it's the perfect way to discover the most beautiful places in the Lazio region by bike.