 Following the end of the Napoleonic wars, he managed to acquire, separately, the two halves of an enormous late 13th-century drawing, showing the original design for the west end, including the unbuilt north-west tower and west gable, and whole of the south-west tower, which had been only partially constructed .He was able to interest Crown Prince Frederick William of Prussia (later King Frederick William IV) in the project, and in 1817 the prince commissioned a report from the architect Karl Friedrich Schinkel.Work on the cathedral was eventually resumed in 1842, and the building was completed towards the end of the 19th century.