Darbu is a village located on the Sørland Line Railway, about midway between Kongsberg and Hokksund. Here is Fiskum Church and the most important heritage is Fiskum Old Church (Fiskum Gamle Kirke).
Fiskum old Church is a medieval, Romanesque church dating from approximately 1200 A.D. The church was dedicated to Saint Olav. Fiskum Old Church was constructed in a rectangular shape and built of stone. It was one of the smaller local churches and used only occasionally in summer. The tower contained 3 bells in 1629, which were changed into to two clocks during 1685-1689.