In 2009, in the little Swiss town of Teufen, conceptual artists Frank and Patrik Riklin converted a 1980s-era nuclear fallout shelter to the “Null Stern Hotel,” an underground facility that accommodates 14 guests in a concrete bunker fitted with blast doors nearly two feet thick.

“We kept the internal structure of the shelter intact — the concrete and the ductwork — and then we added the warmth of antique beds and furniture,” Patrik told the Guardian. “For us it’s an art installation before it’s a hotel — a place where people can think about their surroundings.” There are no windows, only a CCTV camera displaying the outside world, and they retained the institutional paint scheme of pastel blue and yellow.

The site was nominated for best innovation of the year in the 2009 Worldwide Hospitality Awards, and GEO magazine ranked it among the Top 100 hotels in Europe the following year. In 2010 the proprietors were seeking to expand the franchise, but to date no hotel has opened beyond Teufen.