Wasserturm Hotel Cologne

The Wasserturm Hotel Cologne fills a round brick tower, thirty-five and a half metres tall and thirty-four metres across. It stands in Cologne's lively Altstadt-Süd district, with a private garden walling it off from the streets around. Round windows, decorative arches and a fortress-like look mix Rhenish Romanesque with Classicism. Residents took to calling it the Kölsche Engelsburg, their own Castel Sant'Angelo.

Work began in September 1868, after the fast-growing city commissioned the London engineer John Moore to secure clean drinking water. At completion the tower held the largest flat-bottomed tank in Germany and was Europe's tallest water tower. Forged and riveted steel plates formed the 3,650-cubic-metre tank, hung twenty-five metres up within the brick shell. Its concentric double build, an inner vessel inside an outer one, was a first for Germany. That supply was the city's first since Roman times and lasted until about 1930. A wartime hit then reduced the structure to twenty-seven metres, and the ruin stood empty for years. Monument protection, in place since 1983, shaped the conversion that Konrad L. Heinrich began in 1985. He restored the original roof arcades and kept the building's strict geometric form. Five years and twenty million Deutschmarks later, the hotel opened in January 1990 with eighty-eight rooms.

Inside, the lobby rises eleven metres, its levels linked by walkways. Andrée Putman, the Parisian designer, shaped the interiors, and every room and suite follows its own design. Bar Botanik, the rooftop bar, serves cocktails and snacks, while a terrace looks out over the whole city. You reach the Chocolate Museum and the cathedral on a short walk. A restaurant under the glass dome once carried two Michelin stars, and its successor earned one more.