"Onsumslottet" (the "Onsum castle") in St. Halvard street (Oslo) 33, the area also called "Lille Munkengen". Erected in the 1874, demolished 1905. Architects Paul Due and Bernhard Steckmest. Owned by industrialist Oluf Onsum and in 1878 stage for a workers riot (his employees), the Onsum riot.