The Bunker is in Henshaw, right on top of the ridge. It's a small modern conversion, detached. You'll get long views towards Hadrian's Wall from the main room. It faces south-west for the sun.
It sleeps two in one bedroom with a bathroom. It's a Five Star place, so it's been done up to a very high standard with all new fittings. The main living space is downstairs, which some people like and some don't, but it's very light because of the big windows. You access it from the back, through the kitchen.
The hot tub and a fire pit are in the garden. The stairs inside are steep as it's built into the hillside.
You can walk to the Twice Brewed Inn in about five minutes. They do food and have their own brewery. Vindolanda Roman Fort and The Sill Discovery Centre are also a short walk away. Sycamore Gap on Hadrian's Wall is a bit further but reachable on foot.
Hexham is about a twenty-minute drive. It's a nice market town with an abbey, shops and places to eat. Corbridge is similar, a bit closer. For a bigger day out, Kielder Water and Forest Park is about forty minutes north, and the edge of the Lake District is roughly an hour's drive west.
Facilities wise: there's parking, WiFi, a TV, towels and bedding are included, and there's bike storage. No pets.
Useful links for planning: Northumberland National Park and English Heritage for Hadrian's Wall.