Built atop a Roman temple, the Cologne Cathedral is an enormous Roman Catholic cathedral in Cologne, Germany, and the seat of Cologne's Archbishop. Construction began on the cathedral in 1248, and was left unfinished almost two centuries later, in 1473. When construction finally resumed on the cathedral in the 19th century, it was under the order of the majority Protestant court of the Prussian state, following the discovery of the original plans for the building. Celebrations upon the completion of the 632 year construction project took place across Germany, with those in Cologne by far the largest and including Emperor Wilhelm I among the attendees. As such, completing the Cologne Cathedral Causes the Empire to enter a Golden Age, in addition to providing extra Culture and Great Engineer points. It becomes available at Steam Power.