Monschau Castle was probably built at the beginning of the 13th century. In the middle of the 14th century, the complex was extended and enclosed by mighty circular walls and battlements. This almost impregnable fortress of the mighty Counts of Jülich was besieged by Emperor Charles V with heavy artillery in 1543 and finally captured and the town plundered. The castle was only repaired to extend the fortifications of the lower castle.

The French confiscated the castle as national property and sold it. However, the private owners were unable to maintain the extensive complex. They had the roofs removed in 1836/37 in order to be exempt from the building tax. The castle quickly fell into ruin. It was not until the turn of the century that the province attempted to put a stop to the decay. The castle was secured, repaired and renovated.

After the First World War, a youth hostel moved into the west wing. Monschau Castle remains alive and inviting as a "youth castle" to this day.

Christo even wrapped it in 1971, and it becomes the highlight of Monschau when the castle and town are illuminated.