To answer your first question [well, it was my first question anyway]: yes, those are sewer pipes. My ninjas, please.
Welcome to Das Park Hotel in Linz, Austria. This unique hotel has transformed standard concrete sewer pipes into hotel rooms, simply by giving them a back wall and large front door, and drilling a window in the side for a little bit of natural light. Throw in a lamp, a bed, and some sleeping bags and you’ve got yourself what looks like one of the most original hotel ideas that this ninja has ever seen.
The three pipes/rooms are part of a larger hostel/hotel complex, which can be seen in the background of the two images above. My understanding of it is that visitors would normally stay in the main building, but can request the pipes instead [at extra cost? I'm not sure] – you get a key-code for the lock on the room, and enjoy your cylindrical accommodations. All the amenities – showers, toilets, mini bar, cafeteria, etc. are located in the main building.
I’d be interested to know the designer – feel free to enlighten us over here at myninjaplease if you know.
[ed. note: I forgot to mention that the pipes are seasonal - May to October, I believe - as there is no heat/insulation]