The newest Null Stern hotel is open and ready for bookings - and it has no walls, no roof and no bathroom (except for the surrounding meadow).

Ironically named the "Zero Star Hotel", it sits 6,463 feet above sea level in the mountains of Graubunden, Switzerland.

Guests who choose to stay a night at the hotel will not only experience the Swiss Alps in a whole new setting, but will sleep under a night sky filled with stars - weather permitting.

It was designed by Swiss conceptual artists Frank and Patrik Riklin for the Art Safiental land art festival, but has been turned into a bookable experience for $362 a night.

Daniel Charnbonier, who is in charge of hospitality for the Null Stern, said the aim of the hotel was to "put the guest at the centre of the experience and to focus on the intangible by reducing everything else to the minimum."

Guests can expect temperatures to drop to 10-15 degrees Celsius overnight, and the sun to reach the bed by 8:30 in the morning.

A butler service is included with a welcome drink on arrival and a breakfast basket the next day.

The outdoor hotel has certainly reached minimalism. The closest bathroom is a 10 minute walk down the road and the hotel recommends guests "use the meadow for small business."