Cologne Cathedral is a staggering achievement of High Gothic architecture that took over 600 years to complete. Construction began in 1248 but was halted in the 16th century, leaving the building unfinished for nearly 300 years until a wave of 19th-century enthusiasm saw it finally completed in 1880. Its twin spires rise 157 meters into the sky, making it the tallest twin-spired church in the world and the most visited landmark in Germany. The sheer scale of the building is overwhelming: the nave stretches over 144 meters long, and the interior can hold 20,000 worshippers. Miraculously, the cathedral survived World War II largely intact despite the near-total destruction of the surrounding city.

Inside, the atmosphere shifts from architectural grandeur to spiritual intimacy. The Shrine of the Three Kings, a gilded reliquary said to hold the remains of the Biblical Magi, glitters behind the high altar and has drawn pilgrims for eight centuries. Medieval stained glass windows, including the stunning Bavarian Windows, cast jewel-toned light across the stone floor. In 2007, artist Gerhard Richter added a contemporary window made of 11,500 squares of colored glass, creating a shimmering mosaic that bridges past and present.

Pro tip: Climb the 533 steps of the south tower for panoramic views over the Rhine and the city. Stop halfway at the belfry to see the 24-ton St. Peter’s Bell, one of the largest free-swinging church bells in the world. The climb is narrow and steep, so wear comfortable shoes and avoid peak midday hours.