On August 14, 1880, after more than 600 years the construction of the Cologne Cathedral, the most famous landmark in Cologne, Germany, is completed. The World Heritage Site is Germany's most visited landmark, attracting an average of 20,000 people a day. The cathedral is the largest Gothic church in Northern Europe and has the second-tallest spires and largest facade of any church in the world.
K. Patroumpas, and T. Sellis. Current Trends in Database --- Technology EDBT 2006, volume 4254 of Lecture Notes in Computer Science, page 445--464. Springer Berlin / Heidelberg, (2006)