Cologne Cathedral is perhaps the most impressive landmark in the entire state of North Rhine-Westphalia. This masterpiece of Gothic architecture miraculously survived World War II, which reduced much of the city to ruins, and was added to the list of UNESCO World Heritage Sites in 1996, where it became of interest to UNESCO. The Twin Towers soar into the sky and overlook the city centre, the cobblestone streets of the Old Town, Central Station and the main shopping promenade. And while the cathedral's facade is impressive, plenty of great details await inside, including the mausoleum of the Three Wise Men, the treasury, and beautiful stained-glass windows.