Turkish Caves (Cappadocia, Turkey)
Turkey’s five-star Yunak Evleri hotel boasts a labyrinth of ancient fifth and sixth century caves recessed into the limestone cliffs of the Cappadocia region.
Mountaintop Cabin (Italian Alps)
Designed by Italian architect Giovanni Pescamosca, this simple steel-and-wood cabin is free and sleeps nine extreme hikers at a time.
Creepy Catacombs (Paris)
Buried below the streets of Paris, the Catacombs house the bones of over 6 million people and have become one of the eeriest places in Paris.
Jail Hotel (Boston, Massachusetts)
Soaring 90 feet, the jail's central atrium was beautifully preserved and forms the core of the hotel.
Prison Hotel (Stockholm) For the next 250 years it has been used as such, before being closed and converted to unique hotel in 1989.
Sewage Pipe Pods (Ottensheim, Austria)
A unique concept is offering travellers to Germany and Austria accommodation in refurbished sewer pipes.