Cologne Cathedral

Once you stand in front of this imposing structure, you'll understand why it is the most visited landmark in the whole country, with thousands of visitors every day. This gem of Gothic architecture is also the tallest twin-spired church. No wonder it took over seven centuries to finish this outstanding architectural masterpiece.

Even if not a religious person, you should not miss the opportunity to peek inside and marvel at the magnificent decorations and works of art that adorn this cathedral. Worth mentioning are, for example, the Gero Crucifix from the 10th century, The Shrine of the Three Kings, and beautiful stained glass windows.