A Cistercian monastery since 1132, Orval's abbey complex was wrecked in 1793 by anti-religious French Revolutionary soldiers. Rebuilding only started in the early 20th century, part funded by the Trappist beers that have become its trademark. The evocative ancient ruins were conserved and can still be visited along with an 18th-century pharmacy room, the grave of King Wenceslas (1337–83), a medicinal herb garden and an informative museum section that focuses on the beers and their advertising since 1931.
There's also a 20-minute audiovisual on monastic life (in French/Dutch). The brewery section is closed to visitors except for two days in mid-September (book way ahead). However, visitors are welcome to attend offices in the monastery, and it's also possible to stay here (by arrangement) as part of a spiritual retreat (email firstname.lastname@example.org), during which you’re encouraged to join in the daily cycle of prayers.