As you can see, the pigsty (on the left) is in much better condition that the house of its owner (on the right). The cottage has fallen into disrepair and fencing prevents the unwary walker from straying into an area where rotten beams and falling masonry constitute a hazard.
The pigsty, however, has recently been beautifully restored and the curious passerby can get a pig’s eye view with no danger to life or limb.
Although Tegfan and most of the other houses in Dinas kept a pig, this beautiful pigsty is a rarity and the traditional exterior gives no hint of its structure. Once you are inside you can appreciate the roundness and height offered by the beehive design. I was able to stand upright in the centre but couldn’t take a photo that illustrated its shape. This was the best I could do.
The Museum of Wales at St Fagans has more photos (some with pigs), together with information on this unusual style of construction, typically dating from about 1800.
To visit this pigsty walk up the mountain from Dinas, past Machpelah graveyard, until you reach the viewpoint on your right. On your left, on the other side of the road from the viewpoint, there is a narrow path that widens out beyond a gate. Continue for about 200 meters, go through yet another gate and the house will be on your left and the pigsty on your right. While you are there perhaps you could do a little weeding!
Tegfan, Dinas Cross 
I’m grateful to Ann Hughes for this:
Did you notice the dry stone wall as you come up to Penwennol where
the pigsty is? It’s a work of art, but maybe it’s hidden by the growth.
When I saw it, the whole area had been trimmed because the pigsty had
just been restored. It’s amazing how quickly the farmhouse has become a
ruin because we knew the family very well and my mother was a frequent
visitor there. As you say, the pigsty was much better built!
Hi, I’ve been looking for info on this, so thank you very much. I’m not convinced it was actually a pigsty originally though. (An odd sync’ with Frideswide, and her legend of the pigs and striking a healing well at Binsey, near Oxford.) I have been told it is on the spring line. Do you have any further info on it please? I have written to CADW and Coeflin but not had a reply yet.