Deep Sleep Hotel

Reached only on foot through a lantern-lit maze of old mine workings, this is a bed for the night hundreds of feet inside a mountain above Tanygrisiau. There is no signal, no daylight, only the cool hush of the slate and the glow of your headtorch as generations of quarrymen's labour surrounds you. Guests are guided in, share a hearty meal, and wake to the strangest silence in Britain before climbing back to the light. It is bold, atmospheric and genuinely once-in-a-lifetime — the kind of night you'll be recounting for years.

For a category called Unique Stays, nothing beats sleeping deep inside a working mountain of Welsh slate. It is the rare place people would happily cross the country to experience.

• Adventure
• Learn Something New
• Hidden Gem
• History Lovers