"Holy Cologne" as it was known in the Middle Ages, it is a city with more than 1,000 church spires. The Kolner Dom, a 13th Century cathedral is considered one of the most beautiful in the world. Construction of the Dom started in 1248 but stopped in 1599. Finally, in 1842 construction started again and it was completed in 1880. At the time its spires were the tallest in the world.