The Cologne Cathedral is the most popular tourist attraction in Germany -- and one of the largest structures of its kind in the world. It took six centuries to build the cathedral -- but it's never really been "finished." Restoration and reconstruction work is constantly underway -- at a number of workshops near the cathedral.
Stone masons, glass restoration experts, and many others are working to repair or reconstruct parts of the structure that have been damaged by weather, or are simply showing signs of old age. These experts often use modern versions of the tools and materials that were common in the Middle Ages. Our report features interviews with many of those who are involved in this work, including the construction and restoration supervisor. It's the story of a cathedral that has been "under construction" for decades.