This is Ysgubor in Harlech. It's a barn conversion on a working farm. You'll see cattle and sheep in the fields around you. The views are across the valley to the sea, which is about two miles away.
It sleeps five. There are two bedrooms and one bathroom. It's got a 5 Star rating, which means it's well-finished. Underfloor heating, a woodburning stove, that sort of thing. It's semi-detached, so there's another barn next door with the same layout.
The garden is enclosed, which is good if you're bringing dogs. You can have up to two. The driveway is shared with the other barn.
Harlech is a couple of miles down the road. The castle is right in the town. It's a proper fortress on a rock. The Royal St. David's golf course is there too. The nearest shop and pub is about a mile and a half away.
You're right in Snowdonia here. For walking, you can drive into the mountains pretty quickly. The coast path is close, and there are lots of beaches nearby. Barmouth and Shell Island are one way, Black Rock Sands the other.
If you want a day out, Portmeirion is about twenty minutes drive. The Llechwedd slate caverns are similar. Both are interesting. For planning, the Snowdonia National Park site and Cadw page for Harlech Castle are useful.
Inside there's a washing machine, dishwasher, WiFi and TV. Bedding and towels are included. There's a cot and a highchair if you need them. Parking is right outside.