Bohus Fortress sits along lies along the old Norwegian - Swedish border, perched 40 meters (roughly 125 feet) above the surrounding areas and nearly circled by a river that creates a natural sort of moat. Originally built in 1308 at the direction of the Norwegian king, but transferred to Sweden by treaty in 1658.

The walls were upwards of 10 feet thick at the base, and up to 26-40 feet tall, and reinforced after several battles over the years.