Slag is a by-product of copper smelting. Slegghaugan stand as large mountains that are a testament to the huge amount of activity that has taken place over 333 years. Today it is a protected area under the Culture Heritage Act.
If you climb to the top of Slegghaugan, you can enjoy a panoramic view of the Mining-Town. Very close to Slegghaugan is Sleggveien, also referred to as "Pippi Street". An episode of Pippi Long Stocking was filmed here.