World's Most Unusual Hotels

Hotel im Wasserturm, Germany

What It Is: Rising high above Cologne, this 19th-century water tower is one of the tallest in Europe. It was transformed into a chic 78-room hotel in 1990 by French designer Andrée Putman.

The Experience: While there’s still a sense of the water-tower architecture from inside Hotel im Wasserturm’s rooms, they were completely redone. The real magic in the rooms is the 15-foot-tall windows that offer views of the Rhineland. The sight lines are even better from the aptly named Michelin-starred rooftop eatery, La Vision.