Trier has a well-preserved Roman amphitheatre that is the location of an annual theatre/music festival featuring classic Greek writers and operas dealing with ancient myths. The Trier cathedral is home to the Holy Tunic, presumably the robe Jesus wore when he died; the relic is on display every few decades. A Slate Mine Museum located in Fell, just outside Trier, affords visitors an opportunity to experience two typical roof slate mines from around 1900.