Can this the most luxurious, er, down-to-earth hotel ever? At Sala Silvermine in Sweden, you can stay at a mine suite 500 feet below ground. A night’s stay includes a guided tour of ‘winding galleries and thrilling cavities’, plus a basket with cheese, biscuits, fruits, sparkling wine and chocolate. You’ll get to go on a digital detox too since your mobile phone won’t work — the intercom radio to the reception will be your only link to civilization. Sounds really… deep.