Das Park Hotel!

Have you ever seen those huge, concrete drain pipes and thought "Hey, those would make great hotel rooms!"? No? Well, Andreas Strauss did and he created a "hotel" with them. There are 2 Das Hotel locations; one in Austria and one in Germany. The rooms are incredibly minimal with just a bed, lamp and a skylight. The hotel is also unique in that the cost of a room is "what you want to pay". A different idea indeed.
(photos from the Das Hotel website)