Seven unusual hotels you need to add to your bucket list

Palacio de Sal, Bolivia: Deemed the first salt hotel in the world, Palacio de Sal, located 350 km south of Bolivia's capital La Paz, used salt from Salar de Uyuni salt flat to make the luxury hotel. The bed platforms and armchairs in the common area are also made of salt. (Source: palaciodesal/Instagram)

Propeller Island City Lodge, Berlin: Made by artist Lars Stroschen, this bizarre hotel is designed upside-down, as seen in the picture. The hotel also has coffin suites, with coffins for beds, mirrored rooms and furnishings hanging from the ceiling. (Source: taeko_uchida/Instagram)

Das Park Hotel, Austria: This unique hotel in Ottensheim in Austria has rooms made of repurposed drain pipes. Interestingly, the hotel lets you "pay as you wish" to support the project. The place gets breakfast, sanitation and hotel facilties from existing public infrastructure nearby. (Source: furbaby_retreat/Instagram)

Henn-na Hotel, Tokyo: At this hotel, you will be greeted by robot staff who speak in Japanese and English, making it the first such hotel in Japan. Humans, of course, serve as backups in case of malfunction. (Source: kungfucowgirl/Instagram)

Crane Hotel Faralda, Amsterdam: Built on a harbour crane, the hotel features three luxurious design suites on top —Mystique, Secret suite and Free Spirit — along with a studio for parties. The panoramic view from above is of course breathtaking. (Source: hostunusual/Instagram)

Guitar Hotel, Hollywood: A property of Seminole Hard Rock Hotel & Casino, Hollywood, this guitar-shaped hotel was designed by Klai Juba Wald Architecture+Interiors of Las Vegas. Apart from luxury room, it includes a 32,000-square foot rock spa and salon oasis. (Source: guitarhotel/Instagram)

Hotel Costa Verde, Costa Rica: The highlight of this place is an exclusive hotel suite made by refurbishing a vintage 1965 Boeing 727 airframe. The suite jets out from a forest canopy, and will make you feel like you are flying. (Source: hotelcostaverde/Instagram)