Our last night in Yellowstone is the night the bears are lurking. Despite my dad making out like I’m a wuss, I notice he doesn’t leave the motorhome either.

The drives between stops offer their own memorable moments – like a menacingly muscular bison sauntering past our bonnet. But nothing is wilder than Smith Mansion. Propped on an isolated hill above the scenic North Fork Highway, en route to the cowboy town of Cody, this five-storey, mutated cabin looks like something out of a particularly twisted Grimm fairytale. Only Sunny Larsen knows the real story – her dad, whom she calls ‘a modern-day mountain man’, built it, adding floor after floor, with no blueprint, for 22 years. Construction stopped only when he died after accidentally falling from an upper balcony. Sunny now gives tours, determined to ‘protect, preserve and share’ this eccentric chapter of Wyoming’s story.

Approaching the front door, I spot the carcass of a recently mauled mule deer. ‘We have a grizzly problem,’ Sunny nods. ‘They eat fermented apples they find on the ground around here and it gets them drunk.’ Not keen on becoming a sozzled bear’s end-of-binge kebab, I follow Sunny into the house, where she shows me her dad’s interior creations: wooden hammock-style beds, wind chimes made from old railroad ties, logs-turned-dining-table-and-chairs. Her memories of growing up here range from the sublime to the ridiculous – a racoon once moved in and would help itself to dinner on the stove, replacing the saucepan lid afterwards – and we end the tour gazing out from one of the uppermost, open-sided platforms, ranches and snow-speckled mountains spread as far as the eye can make out.