Breigangsgruva is located in Skien and is known as Fossum's largest and deepest mine. It has great historical significance related to ore mining and has been protected as a technical cultural monument. The mine was established in the 19th century and served as housing for families who worked there. The main income came from Fossum Verk, which was an important player in the area.
The mine is characterized by fenced open pits and deep shafts, which are unusually large compared to other mines in Fossum. Ruins and rubble in the area testify to the former activity and provide an insight into the history of the mine. Breigangsgruva represents an important chapter in the region's industrial development and cultural history.