Wasserturm Hotel Cologne, Curio Collection by Hilton

This 11-story brick water tower, the tallest in Europe, must have seemed like an unlikely candidate for the sort of industrial renovation that is sweeping Germany—but punch some holes in the sides for windows, drop a restaurant on the roof, and you've got yourself a striking and stylish luxury hotel.

Of course it doesn't hurt to have Andrée Putman calling the shots in the interiors; her decidedly Parisian, vaguely Deco influence has transformed what could have been a cold and alien environment into a comfortable and inviting space, full of rich textures and curvaceous furniture. The circular form of the tower's outer wall makes for some unusual and inventive floor plans, a welcome break from the box construction that seems so sensible in square hotels; but aside from that fact, it's everything you would expect from a top-class hotel—including wireless internet, round-the clock room service, sauna and massage, limo transfers, and perhaps most thoughtful of all, morning papers in a variety of languages.

The Michelin-starred top-floor restaurant offers stunning panoramic views of Cologne, and the location, in a park just outside the city center, means it's not hemmed-in by skyscrapers or construction cranes, and lends a sort of resort feel to the hotel, a buffer from the bustle of downtown. Still, the location is convenient enough that the ground-floor Harry's Lounge, richly decorated in red and black leather, is a meeting point for locals and guests alike.