Holzheim Castle dates to 1333, and its owners were vassals of the Duchy of Jülich. In the 15th to 17th centuries the manor house and gate tower were built, both of which have survived. In 1818, when the region was part of the Prussia county of Düren, the castle and its estates were sold to private buyers. In 1893 it was bought by Richard Schleicher, who also bought the nearby estate of Schönthal. The property later changed hands several times.
References:Goryōkaku (五稜郭) (literally, 'five-point fort') is a star fort in the Japanese city of Hakodate on the island of Hokkaido. The fortress was completed in 1866. It was the main fortress of the short-lived Republic of Ezo.
Goryōkaku was designed in 1855 by Takeda Ayasaburō and Jules Brunet. Their plans was based on the work of the French architect Vauban. The fortress was completed in 1866, two years before the collapse of the Tokugawa Shogunate. It is shaped like a five-pointed star. This allowed for greater numbers of gun emplacements on its walls than a traditional Japanese fortress, and reduced the number of blind spots where a cannon could not fire.
The fort was built by the Tokugawa shogunate to protect the Tsugaru Strait against a possible invasion by the Meiji government.
Goryōkaku is famous as the site of the last battle of the Boshin War.