World's Most Secret Hotels 2x2

Visits to a fortress-style hotel in the Empty Quarter in the United Arab Emirates, a minimalist hotel on the tranquil banks of a Norwegian river, a futuristic fantasy with three bespoke treehouses in Dorset woodland, an eco-friendly yellow submarine on the river banks of County Monaghan in Ireland, and a luxury hotel fashioned from repurposed shipping containers in the New South Wales Australian outback.