Cologne Cathedral.

Cologne Cathedral, a UNESCO World Heritage Site, is a stunning example of Gothic architecture in Cologne, Germany. Construction began in 1248 and, after numerous interruptions, was completed in 1880, making it one of the longest ongoing building projects in history. Its impressive twin spires rise 515 feet, marking it as the tallest twin-spired church globally. The cathedral houses remarkable treasures, including the Shrine of the Three Wise Men and exquisite stained-glass windows dating back to the 13th century, along with contemporary works by artists like Gerhard Richter. Visitors can explore its grand interior, climb 533 steps for breathtaking views, and marvel at its rich artistic heritage, making it a must-see landmark that attracts millions each year.