The castle of Mosonmagyaróvár (German: Schloss Wieselburg-Ungarisch Altenburg) is a medieval castle that has survived intact. The castles of Moson played a very important military role in the Lake Fertő and the Moson-Danube region during the Middle Ages, and archaeological excavations have brought to light many forgotten facts about them.
King Stephen built his early castle on a low rise, now called King's Hill. Like the nationally known castles of the Ispanic region, the Moson castle consisted of walls made of wooden piles with a diaphragm construction and filled with earth, with the houses of the county administration in the inner courtyard. Its role as a control centre was taken over by a private landowner's fortress, built of stone in the post-Tatar period.
Source of text and images: https://hu.wikipedia.org/wiki/Mosonmagyar%C3%B3v%C3%A1ri_v%C3%A1r