Flattum is a village in Modum Municipality, in Buskerud, Norway. Flattum lies at 146 m above sea level, 2.1 km from the Finnemarka mountains. The nearest city is Drammen, 31 km to the southeast. Among the landmarks around are Blaafarveværket (11.6 km), Royal Palace (42 km) and Akershus Fortress (42 km). Among the natural features are Snarumselva (6.7 km) and Hønefossen (24 km).