How many years did it take to complete Cologne Cathedral, from its groundbreaking in 1248 to its finish in 1880?

Answer

632 years

Construction stalled entirely for nearly 400 years, and a medieval wooden crane sat abandoned atop the unfinished tower for so long that it became a fixture of the city skyline. When finally completed in 1880, it was the tallest building in the world for four years.

Source: UNESCO World Heritage Centre