There are some very unusual hotels through out the world. If you have only stayed in traditional hotels then it may be a nice change to stay somewhere with a great unique feature.
There are all sorts of unique hotels over the world. One of the most unusual must be the salt hotel in Bolivia. All of the building, floors and furniture are made completely of salt. There is a spa and salt sculptures and even a salt golf course. This certainly would be a unique experience.
If you want to stay somewhere really cool then there are a series of cave hotels in various places throughout the world. Some are ancient dwelling places and others have been made specially to be turned in to hotel rooms. Their underground location means that they are not exposed to the sun and so can be a lovely cool retreat in a hot country.
There are also a series of hotels built of ice or made from igloos. These are obviously situated in cold countries such as Switzerland, Finland and Canada and are certainly something a bit different. In Finland you can watch the northern lights through the transparent walls of the igloo or stay in the original ice hotel in Sweden.
There are also a selection of tree houses, sewage tubes, wigwams and lighthouses if you want something a bit different. It can be as much fun choosing these exotic places as it can be staying in them. It is worth noting that a strange hotel like his could be lots of fun for some but not for others. Think carefully about the facilities they offer and whether it would suit you. Maybe it could be better to just spend one night in a novelty place and the rest of the time in a more traditional hotel if you are not sure.