Fort 4 in Mortsel is one of the Brialmont forts, constructed between 1860 and 1864 from brick and sandstone as part of Antwerp's defensive strategy. Built following military engineer Henri Alexis Brialmont's plan to defend the city against future threats, this fortress comprises a sprawling 24-hectare domain. During World War I, the fort endured heavy German bombardment on October 8, 1914, and was abandoned by Belgian troops that night. In World War II, the Germans used it to store ammunition and aircraft bombs, and it suffered repeated bomb damage including strikes from V-weapons after Antwerp's liberation. Transferred to Mortsel's municipal ownership in 2000, the fort today functions as a park with guided tours available to visitors.