 Furthermore, in this area of the country are El Teniente, the most underground mine of copper in the world, and the mining town of Sewell, declared a World Heritage Site by UNESCO in 2006.Further south in the Maule and Bio Bio regions are the Radal Siete Tazas National Reserve and Laguna del Laja National Park.Araucanía Region is the heartland of the Mapuche people.