One weekend per year Orval holds an open door day where they allow a guided visit of their brewery. Orval is a Cistercian monastic community. Nestled into the southern Ardennes at the far southern tip of Belgium, the Orval abbey is breathtaking. A regular visit to the abbey allows the visitor to see the abbey ruins, and to tour the visitor center where the history of the abbey is explained, and there are brewing and cheese-making exhibits. Just down the road is an inn where you can sample some Orval beer and cheese.
Normally, brewery visits are not offered; the visit at Orval during the open door day was a self-guided tour. Signs explain the process of brewing, although they are in Dutch and French only. You can sign up from the Orval website; they usually begin the process a few months before their open door day. I'm going to keep my rambling short. If you aren't around during the time of the open door days, you can still visit the public areas of the abbey. Check their website for additional details.
Driving is probably the most straightforward way of visiting. Public transport is possible, but not easily accessible since trains from the Brussels area can take up to 3 hours to arrive, and busses may run infrequently. I'm not sure about biking because I haven't found any organized bike routes through the Wallonian regions. The abbey is very well maintained, Orval beer is some of the most delicious and unique in Belgium, and while exploring the ruins won't take all day, the area has plenty of hiking.
Love the Orval paraphernalia.
The stained glass is impressive.
Checking out the abbey ruins.
Story of the fountain and the history of Orval here (including trout with the ring).